task_url stringlengths 30 116 | task_name stringlengths 2 86 | task_description stringlengths 0 14.4k | language_url stringlengths 2 53 | language_name stringlengths 1 52 | code stringlengths 0 61.9k |
|---|---|---|---|---|---|
http://rosettacode.org/wiki/Babbage_problem | Babbage problem |
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example:
What is the smallest positive integer whose square ends in the digits 269,696?
— Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p.... | #Processing | Processing | // Lines that begin with two slashes, thus, are comments: they
// will be ignored by the machine.
// First we must declare a variable, n, suitable to store an integer:
int n;
// Each statement we address to the machine must end with a semicolon.
// To begin with, the value of n will be zero:
n = 0;
// Now w... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Groovy | Groovy | class Approximate {
private static boolean approxEquals(double value, double other, double epsilon) {
return Math.abs(value - other) < epsilon
}
private static void test(double a, double b) {
double epsilon = 1e-18
System.out.printf("%f, %f => %s\n", a, b, approxEquals(a, b, epsilo... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Haskell | Haskell | class (Num a, Ord a, Eq a) => AlmostEq a where
eps :: a
infix 4 ~=
(~=) :: AlmostEq a => a -> a -> Bool
a ~= b = or [ a == b
, abs (a - b) < eps * abs(a + b)
, abs (a - b) < eps ]
instance AlmostEq Int where eps = 0
instance AlmostEq Integer where eps = 0
instance AlmostEq Double where eps... |
http://rosettacode.org/wiki/Balanced_brackets | Balanced brackets | Task:
Generate a string with N opening brackets [ and with N closing brackets ], in some arbitrary order.
Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples
(empty) ... | #CLU | CLU | % This program needs the random number generator from
% "misc.lib" that comes with PCLU.
shuffle = proc [T: type] (a: array[t])
aT = array[t]
for i: int in int$from_to_by(aT$size(a)-1,0,-1) do
x: int := aT$low(a) + i
y: int := aT$low(a) + random$next(i+1)
temp: T := a[x]
a[x] ... |
http://rosettacode.org/wiki/Append_a_record_to_the_end_of_a_text_file | Append a record to the end of a text file | Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files,... | #Batch_File | Batch File |
@echo off
(
echo jsmith:x:1001:1000:Joe Smith,Room 1007,^(234^)555-8917,^(234^)555-0077,jsmith@rosettacode.org:/home/jsmith:/bin/bash
echo jdoe:x:1002:1000:Jane Doe,Room 1004,^(234^)555-8914,^(234^)555-0044,jdoe@rosettacode.org:/home/jdoe:/bin/bash
) > append.txt
echo Current contents of append.txt:
type appe... |
http://rosettacode.org/wiki/Append_a_record_to_the_end_of_a_text_file | Append a record to the end of a text file | Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files,... | #C | C | #include <stdio.h>
#include <string.h>
/* note that UID & GID are of type "int" */
typedef const char *STRING;
typedef struct{STRING fullname, office, extension, homephone, email; } gecos_t;
typedef struct{STRING account, password; int uid, gid; gecos_t gecos; STRING directory, shell; } passwd_t;
#define GECOS_FMT "%... |
http://rosettacode.org/wiki/Associative_array/Creation | Associative array/Creation | Task
The goal is to create an associative array (also known as a dictionary, map, or hash).
Related tasks:
Associative arrays/Iteration
Hash from two arrays
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element ins... | #Aikido | Aikido |
var names = {} // empty map
names["foo"] = "bar"
names[3] = 4
// initialized map
var names2 = {"foo": bar, 3:4}
// lookup map
var name = names["foo"]
if (typeof(name) == "none") {
println ("not found")
} else {
println (name)
}
// remove from map
delete names["foo"]
|
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #AArch64_Assembly | AArch64 Assembly |
/* ARM assembly AARCH64 Raspberry PI 3B */
/* program antiprime64.s */
/************************************/
/* Constantes */
/************************************/
.include "../includeConstantesARM64.inc"
.equ NMAXI, 20
.equ MAXLINE, 5
/*********************************/
/* In... |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #Action.21 | Action! | BYTE FUNC CountDivisors(INT a)
INT i
BYTE prod,count
prod=1 count=0
WHILE a MOD 2=0
DO
count==+1
a==/2
OD
prod==*(1+count)
i=3
WHILE i*i<=a
DO
count=0
WHILE a MOD i=0
DO
count==+1
a==/i
OD
prod==*(1+count)
i==+2
OD
IF a>2 THEN
prod==*2
FI
R... |
http://rosettacode.org/wiki/Atomic_updates | Atomic updates |
Task
Define a data type consisting of a fixed number of 'buckets', each containing a nonnegative integer value, which supports operations to:
get the current value of any bucket
remove a specified amount from one specified bucket and add it to another, preserving the total of all bucket values, and clamping the t... | #FreeBASIC | FreeBASIC | Randomize Timer
Dim Shared As Uinteger cubo(1 To 10), a, i
For i As Uinteger = 1 To 10
cubo(i) = Int(Rnd * 90)
Next i
Function Display(cadena As String) As Uinteger
Dim As Uinteger valor
Print cadena; Spc(2);
For i As Uinteger = 1 To 10
valor += cubo(i)
Print Using "###"; cubo(i);
... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Dyalect | Dyalect | var x = 42
assert(42, x) |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #E | E | require(a == 42) # default message, "Required condition failed"
require(a == 42, "The Answer is Wrong.") # supplied message
require(a == 42, fn { `Off by ${a - 42}.` }) # computed only on failure |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #EchoLisp | EchoLisp |
(assert (integer? 42)) → #t ;; success returns true
;; error and return to top level if not true;
(assert (integer? 'quarante-deux))
⛔ error: assert : assertion failed : (#integer? 'quarante-deux)
;; assertion with message (optional)
(assert (integer? 'quarante-deux) "☝️ expression must evaluate to the integer 42... |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #Ada | Ada | with Ada.Text_Io;
with Ada.Integer_text_IO;
procedure Call_Back_Example is
-- Purpose: Apply a callback to an array
-- Output: Prints the squares of an integer array to the console
-- Define the callback procedure
procedure Display(Location : Positive; Value : Integer) is
begin
Ada.Text... |
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #M2000_Interpreter | M2000 Interpreter |
Module Checkit {
\\ find mode
Function GetMode {
Inventory N
Inventory ALLMODES
m=1
While not empty {
if islet then {
Read A$
if Exist(N, A$) then {
k=Eval(N)
... |
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #Maple | Maple | Statistics:-Mode([1, 2.1, 2.1, 3]);
Statistics:-Mode([1, 2.1, 2.1, 3.2, 3.2, 5]); |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #BASIC256 | BASIC256 | REM Store some values with their keys:
PROCputdict(mydict$, "FF0000", "red")
PROCputdict(mydict$, "00FF00", "green")
PROCputdict(mydict$, "0000FF", "blue")
REM Iterate through the dictionary:
i% = 1
REPEAT
i% = FNdict(mydict$, i%, v$, k$)
PRINT v$, k$
UN... |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #BBC_BASIC | BBC BASIC | REM Store some values with their keys:
PROCputdict(mydict$, "FF0000", "red")
PROCputdict(mydict$, "00FF00", "green")
PROCputdict(mydict$, "0000FF", "blue")
REM Iterate through the dictionary:
i% = 1
REPEAT
i% = FNdict(mydict$, i%, v$, k$)
PRINT v$, k$
UN... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #Common_Lisp | Common Lisp | (defparameter a #(1.00000000L0 -2.77555756L-16 3.33333333L-01 -1.85037171L-17))
(defparameter b #(0.16666667L0 0.50000000L0 0.50000000L0 0.16666667L0))
(defparameter s #(-0.917843918645 0.141984778794 1.20536903482 0.190286794412 -0.662370894973
-1.00700480494 -0.404707073677 0.800482325044 0.74... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #D | D | import std.stdio;
alias T = real;
alias AT = T[];
AT filter(const AT a, const AT b, const AT signal) {
AT result = new T[signal.length];
foreach (int i; 0..signal.length) {
T tmp = 0.0;
foreach (int j; 0..b.length) {
if (i-j<0) continue;
tmp += b[j] * signal[i-j];
... |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #BQN | BQN | Avg ← +´÷≠
Avg 1‿2‿3‿4 |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #C | C | #include <stdio.h>
double mean(double *v, int len)
{
double sum = 0;
int i;
for (i = 0; i < len; i++)
sum += v[i];
return sum / len;
}
int main(void)
{
double v[] = {1, 2, 2.718, 3, 3.142};
int i, len;
for (len = 5; len >= 0; len--) {
printf("mean[");
for (i = 0; i < len; i++)
printf(i ? ", %g" : "%... |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Lua | Lua | base = {name="Rocket Skates", price=12.75, color="yellow"}
update = {price=15.25, color="red", year=1974}
--[[ clone the base data ]]--
result = {}
for key,val in pairs(base) do
result[key] = val
end
--[[ copy in the update data ]]--
for key,val in pairs(update) do
result[key] = val
end
--[[ print the res... |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | a1 = <|"name" -> "Rocket Skates", "price" -> 12.75, "color" -> "yellow"|>;
a2 = <|"price" -> 15.25, "color" -> "red", "year" -> 1974|>;
Merge[{a1, a2}, Last] |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #MiniScript | MiniScript | base = {"name":"Rocket Skates", "price":12.75, "color":"yellow"}
update = {"price":15.25, "color":"red", "year":1974}
result = base + update
print result |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | Grid@Prepend[
Table[{n, #[[1]], #[[2]],
Row[{Round[10000 Abs[#[[1]] - #[[2]]]/#[[2]]]/100., "%"}]} &@
N[{Mean[Array[
Length@NestWhileList[#, 1, UnsameQ[##] &, All] - 1 &[# /.
MapIndexed[#2[[1]] -> #1 &,
RandomInteger[{1, n}, n]] &] &, 10000]],
Sum[n! n^(n - k - 1)/... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Nim | Nim | import random, math, strformat
randomize()
const
maxN = 20
times = 1_000_000
proc factorial(n: int): float =
result = 1
for i in 1 .. n:
result *= i.float
proc expected(n: int): float =
for i in 1 .. n:
result += factorial(n) / pow(n.float, i.float) / factorial(n - i)
proc test(n, times: int):... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Oberon-2 | Oberon-2 |
MODULE AvgLoopLen;
(* Oxford Oberon-2 *)
IMPORT Random, Out;
PROCEDURE Fac(n: INTEGER; f: REAL): REAL;
BEGIN
IF n = 0 THEN
RETURN f
ELSE
RETURN Fac(n - 1,n*f)
END
END Fac;
PROCEDURE Power(n,i: INTEGER): REAL;
VAR
p: REAL;
BEGIN
p := 1.0;
WHILE i > 0 DO p := p * n; DEC(i) END;
RETURN p
END Power;
PROC... |
http://rosettacode.org/wiki/Averages/Simple_moving_average | Averages/Simple moving average | Computing the simple moving average of a series of numbers.
Task[edit]
Create a stateful function/class/instance that takes a period and returns a routine that takes a number as argument and returns a simple moving average of its arguments so far.
Description
A simple moving average is a method for computing an avera... | #REXX | REXX | /*REXX program illustrates and displays a simple moving average using a constructed list*/
parse arg p q n . /*obtain optional arguments from the CL*/
if p=='' | p=="," then p= 3 /*Not specified? Then use the default.*/
if q=='' | q=="," then q= 5 ... |
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Go | Go | package main
import "fmt"
func isPrime(n int) bool {
switch {
case n < 2:
return false
case n%2 == 0:
return n == 2
case n%3 == 0:
return n == 3
default:
d := 5
for d*d <= n {
if n%d == 0 {
return false
}
... |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #Lua | Lua |
local times = {"23:00:17","23:40:20","00:12:45","00:17:19"}
-- returns time converted to a radian format
local function timeToAngle(str)
local h,m,s = str:match("(..):(..):(..)")
return (h + m / 60 + s / 3600)/12 * math.pi
end
-- computes the mean of the angles inside a list
local function meanAngle(angles)
lo... |
http://rosettacode.org/wiki/AVL_tree | AVL tree |
This page uses content from Wikipedia. The original article was at AVL tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In computer science, an AVL tree is a self-balancing binary search tree.... | #Objeck | Objeck | class AVLNode {
@key : Int;
@balance : Int;
@height : Int;
@left : AVLNode;
@right : AVLNode;
@above : AVLNode;
New(key : Int, above : AVLNode) {
@key := key;
@above := above;
}
method : public : GetKey() ~ Int {
return @key;
}
method : public : GetLeft() ~ AVLNode {
return @... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #Kotlin | Kotlin | // version 1.0.5-2
fun meanAngle(angles: DoubleArray): Double {
val sinSum = angles.sumByDouble { Math.sin(it * Math.PI / 180.0) }
val cosSum = angles.sumByDouble { Math.cos(it * Math.PI / 180.0) }
return Math.atan2(sinSum / angles.size, cosSum / angles.size) * 180.0 / Math.PI
}
fun main(args: Array<S... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #Liberty_BASIC | Liberty BASIC | global Pi
Pi =3.1415926535
print "Mean Angle( "; chr$( 34); "350,10"; chr$( 34); ") = "; using( "###.#", meanAngle( "350,10")); " degrees." ' 0
print "Mean Angle( "; chr$( 34); "90,180,270,360"; chr$( 34); ") = "; using( "###.#", meanAngle( "90,180,270,360")); " degrees." ' -90
pr... |
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #EasyLang | EasyLang | func quickselect k . list[] res .
#
subr partition
swap list[(left + right) / 2] list[left]
mid = left
for i = left + 1 to right
if list[i] < list[left]
mid += 1
swap list[i] list[mid]
.
.
swap list[left] list[mid]
.
left = 0
right = len list[] - 1
while left... |
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #EchoLisp | EchoLisp |
(define (median L) ;; O(n log(n))
(set! L (vector-sort! < (list->vector L)))
(define dim (// (vector-length L) 2))
(if (integer? dim)
(// (+ [L dim] [L (1- dim)]) 2)
[L (floor dim)]))
(median '( 3 4 5))
→ 4
(median '(6 5 4 3))
→ 4.5
(median (iota 10000))
→ 4999.5
(median (iota 10001))
→ 5000
|
http://rosettacode.org/wiki/Averages/Pythagorean_means | Averages/Pythagorean means | Task[edit]
Compute all three of the Pythagorean means of the set of integers 1 through 10 (inclusive).
Show that
A
(
x
1
,
…
,
x
n
)
≥
G
(
x
1
,
…
,
x
n
)
≥
H
(
x
1
,
…
,
x
n
)
{\displaystyle A(x_{1},\ldots ,x_{n})\geq G(x_{1},\ldots ,x_{n})\geq H(x_{1},\ldots ,x_{n})}
for this set of p... | #Icon_and_Unicon | Icon and Unicon | link numbers # for a/g/h means
procedure main()
every put(x := [], 1 to 10)
writes("x := [ "); every writes(!x," "); write("]")
write("Arithmetic mean:", a := amean!x)
write("Geometric mean:",g := gmean!x)
write("Harmonic mean:", h := hmean!x)
write(" a >= g >= h is ", if a >= g >= h then "true" else "false")
e... |
http://rosettacode.org/wiki/Balanced_ternary | Balanced ternary | Balanced ternary is a way of representing numbers. Unlike the prevailing binary representation, a balanced ternary integer is in base 3, and each digit can have the values 1, 0, or −1.
Examples
Decimal 11 = 32 + 31 − 30, thus it can be written as "++−"
Decimal 6 = 32 − 31 + 0 × 30, thus it can be written as "+−0"
... | #OCaml | OCaml | type btdigit = Pos | Zero | Neg
type btern = btdigit list
let to_string n =
String.concat ""
(List.rev_map (function Pos -> "+" | Zero -> "0" | Neg -> "-") n)
let from_string s =
let sl = ref [] in
let digit = function '+' -> Pos | '-' -> Neg | '0' -> Zero
| _ -> failwith "invalid digit" in
... |
http://rosettacode.org/wiki/Babbage_problem | Babbage problem |
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example:
What is the smallest positive integer whose square ends in the digits 269,696?
— Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p.... | #Prolog | Prolog | :- use_module(library(clpfd)).
babbage_(B, B, Sq) :-
B * B #= Sq,
number_chars(Sq, R),
append(_, ['2','6','9','6','9','6'], R).
babbage_(B, R, Sq) :-
N #= B + 1,
babbage_(N, R, Sq).
babbage :-
once(babbage_(1, Num, Square)),
format('lowest number is ~p which squared becomes ~p~n', [Num, Square]). |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #J | J |
NB. default comparison tolerance matches the python result
".;._2]0 :0
100000000000000.01 = 100000000000000.011
100.01 = 100.011
(10000000000000.001 % 10000.0) = 1000000000.0000001000
0.001 = 0.0010000001
0.000000000000000000000101 = 0.0
(= (... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Java | Java | public class Approximate {
private static boolean approxEquals(double value, double other, double epsilon) {
return Math.abs(value - other) < epsilon;
}
private static void test(double a, double b) {
double epsilon = 1e-18;
System.out.printf("%f, %f => %s\n", a, b, approxEquals(a, ... |
http://rosettacode.org/wiki/Balanced_brackets | Balanced brackets | Task:
Generate a string with N opening brackets [ and with N closing brackets ], in some arbitrary order.
Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples
(empty) ... | #COBOL | COBOL | IDENTIFICATION DIVISION.
PROGRAM-ID. test-balanced-brackets.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 True-Val CONSTANT 0.
01 False-Val CONSTANT 1.
LOCAL-STORAGE SECTION.
01 current-time PIC 9(10).
01 bracket-type PIC 9.
... |
http://rosettacode.org/wiki/Append_a_record_to_the_end_of_a_text_file | Append a record to the end of a text file | Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files,... | #C.23 | C# | using System;
using System.IO;
namespace AppendPwdRosetta
{
class PasswordRecord
{
public string account, password, fullname, office, extension, homephone, email, directory, shell;
public int UID, GID;
public PasswordRecord(string account, string password, int UID, int GID, string full... |
http://rosettacode.org/wiki/Associative_array/Creation | Associative array/Creation | Task
The goal is to create an associative array (also known as a dictionary, map, or hash).
Related tasks:
Associative arrays/Iteration
Hash from two arrays
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element ins... | #Aime | Aime | record r; |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #Ada | Ada | with Ada.Text_IO; use Ada.Text_IO;
procedure Antiprimes is
function Count_Divisors (N : Integer) return Integer is
Count : Integer := 1;
begin
for i in 1 .. N / 2 loop
if N mod i = 0 then
Count := Count + 1;
end if;
end loop;
return Count;
end Count_Div... |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #ALGOL_68 | ALGOL 68 | BEGIN # find some anti-primes: numbers with more divisors than the #
# previous numbers #
INT max number := 10 000;
INT max divisors := 0;
# construct a table of the divisor counts #
[ 1 : max number ]INT ndc; FOR i FROM ... |
http://rosettacode.org/wiki/Atomic_updates | Atomic updates |
Task
Define a data type consisting of a fixed number of 'buckets', each containing a nonnegative integer value, which supports operations to:
get the current value of any bucket
remove a specified amount from one specified bucket and add it to another, preserving the total of all bucket values, and clamping the t... | #Go | Go | package main
import (
"fmt"
"math/rand"
"sync"
"time"
)
const nBuckets = 10
type bucketList struct {
b [nBuckets]int // bucket data specified by task
// transfer counts for each updater, not strictly required by task but
// useful to show that the two updaters get fair chances to run... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #ECL | ECL |
ASSERT(a = 42,'A is not 42!',FAIL); |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Eiffel | Eiffel | class MAIN
creation main
feature main is
local
test: TEST;
do
create test;
io.read_integer;
test.assert(io.last_integer);
end
end |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Elixir | Elixir | ExUnit.start
defmodule AssertionTest do
use ExUnit.Case
def return_5, do: 5
test "not equal" do
assert 42 == return_5
end
end |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #Aime | Aime | void
map(list l, void (*fp)(object))
{
l.ucall(fp, 0);
}
void
out(object o)
{
o_(o, "\n");
}
integer
main(void)
{
list(0, 1, 2, 3).map(out);
return 0;
} |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #ALGOL_68 | ALGOL 68 | PROC call back proc = (INT location, INT value)VOID:
(
printf(($"array["g"] = "gl$, location, value))
);
PROC map = (REF[]INT array, PROC (INT,INT)VOID call back)VOID:
(
FOR i FROM LWB array TO UPB array DO
call back(i, array[i])
OD
);
main:
(
[4]INT array := ( 1, 4, 9, 16 );
map(array,... |
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | Commonest[{b, a, c, 2, a, b, 1, 2, 3}]
Commonest[{1, 3, 2, 3}] |
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #MATLAB | MATLAB | function modeValue = findmode(setOfValues)
modeValue = mode(setOfValues);
end |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #Bracmat | Bracmat | ( new$hash:?myhash
& (myhash..insert)$(title."Some title")
& (myhash..insert)$(formula.a+b+x^7)
& (myhash..insert)$(fruit.apples oranges kiwis)
& (myhash..insert)$(meat.)
& (myhash..insert)$(fruit.melons bananas)
& (myhash..remove)$formula
& (myhash..insert)$(formula.x^2+y^2)
& (myhash..forall)
$ (
= key va... |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #Brat | Brat | h = [ hello: 1 world: 2 :! : 3]
#Iterate over key, value pairs
h.each { k, v |
p "Key: #{k} Value: #{v}"
}
#Iterate over keys
h.each_key { k |
p "Key: #{k}"
}
#Iterate over values
h.each_value { v |
p "Value: #{v}"
} |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #FreeBASIC | FreeBASIC | Sub Filtro(a() As Double, b() As Double, senal() As Double, resultado() As Double)
Dim As Integer j, k
Dim As Double tmp
For j = 0 To Ubound(senal)
tmp = 0
For k = 0 To Ubound(b)
If (j-k < 0) Then Continue For
tmp = tmp + b(k) * senal(j-k)
Next k
For... |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #C.23 | C# | using System;
using System.Linq;
class Program
{
static void Main()
{
Console.WriteLine(new[] { 1, 2, 3 }.Average());
}
} |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #C.2B.2B | C++ | #include <vector>
double mean(const std::vector<double>& numbers)
{
if (numbers.size() == 0)
return 0;
double sum = 0;
for (std::vector<double>::iterator i = numbers.begin(); i != numbers.end(); i++)
sum += *i;
return sum / numbers.size();
} |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Nim | Nim | import tables
let t1 = {"name": "Rocket Skates", "price": "12.75", "color": "yellow"}.toTable
let t2 = {"price": "15.25", "color": "red", "year": "1974"}.toTable
var t3 = t1 # Makes a copy.
for key, value in t2.pairs:
t3[key] = value
echo t3 |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Objective-C | Objective-C | #import <Foundation/Foundation.h>
int main(void) {
@autoreleasepool {
NSDictionary *base = @{@"name": @"Rocket Skates", @"price": @12.75, @"color": @"yellow"};
NSDictionary *update = @{@"price": @15.25, @"color": @"red", @"year": @1974};
NSMutableDictionary *result = [[NSMutableDictionary alloc] initW... |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #OCaml | OCaml |
type ty =
| TFloat of float
| TInt of int
| TString of string
type key = string
type assoc = string * ty
let string_of_ty : ty -> string = function
| TFloat x -> string_of_float x
| TInt i -> string_of_int i
| TString s -> s
let print_pair key el =
Printf.printf "%s: %s\n" key (stri... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #PARI.2FGP | PARI/GP | expected(n)=sum(i=1,n,n!/(n-i)!/n^i,0.);
test(n, times)={
my(ct);
for(i=1,times,
my(x=1,bits);
while(!bitand(bits,x),ct++; bits=bitor(bits,x); x = 1<<random(n))
);
ct
};
TIMES=1000000;
{for(n=1,20,
my(cnt=test(n, TIMES),avg=cnt/TIMES,ex=expected(n),diff=(avg/ex-1)*100.);
print(n"\t"avg*1."\t"ex*1."\t"... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Perl | Perl | use List::Util qw(sum reduce);
sub find_loop {
my($n) = @_;
my($r,@seen);
while () { $seen[$r] = $seen[($r = int(1+rand $n))] ? return sum @seen : 1 }
}
print " N empiric theoric (error)\n";
print "=== ========= ============ =========\n";
my $MAX = 20;
my $TRIALS = 1000;
for my $n... |
http://rosettacode.org/wiki/Averages/Simple_moving_average | Averages/Simple moving average | Computing the simple moving average of a series of numbers.
Task[edit]
Create a stateful function/class/instance that takes a period and returns a routine that takes a number as argument and returns a simple moving average of its arguments so far.
Description
A simple moving average is a method for computing an avera... | #Ring | Ring |
load "stdlib.ring"
decimals(8)
maxperiod = 20
nums = newlist(maxperiod,maxperiod)
accum = list(maxperiod)
index = list(maxperiod)
window = list(maxperiod)
for i = 1 to maxperiod
index[i] = 1
accum[i] = 0
window[i] = 0
next
for i = 1 to maxperiod
for j = 1 to maxperiod
nums[i][j] = 0
next
n... |
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Groovy | Groovy | class AttractiveNumbers {
static boolean isPrime(int n) {
if (n < 2) return false
if (n % 2 == 0) return n == 2
if (n % 3 == 0) return n == 3
int d = 5
while (d * d <= n) {
if (n % d == 0) return false
d += 2
if (n % d == 0) return false
... |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | meanTime[list_] :=
StringJoin@
Riffle[ToString /@
Floor@{Mod[24 #, 24], Mod[24*60 #, 60], Mod[24*60*60 #, 60]} &[
Arg[Mean[
Exp[FromDigits[ToExpression@StringSplit[#, ":"], 60] & /@
list/(24*60*60) 2 Pi I]]]/(2 Pi)], ":"];
meanTime[{"23:00:17", "23:40:20", "00:12:45", "00:17:19"}... |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #MATLAB_.2F_Octave | MATLAB / Octave | function t = mean_time_of_day(t)
c = pi/(12*60*60);
for k=1:length(t)
a = sscanf(t{k},'%d:%d:%d');
phi(k) = (a(1)*3600+a(2)*60+a(3));
end;
d = angle(mean(exp(i*phi*c)))/(2*pi); % days
if (d<0) d += 1;
t = datestr(d,"HH:MM:SS");
end; |
http://rosettacode.org/wiki/AVL_tree | AVL tree |
This page uses content from Wikipedia. The original article was at AVL tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In computer science, an AVL tree is a self-balancing binary search tree.... | #Objective-C | Objective-C |
@implementation AVLTree
-(BOOL)insertWithKey:(NSInteger)key {
if (self.root == nil) {
self.root = [[AVLTreeNode alloc]initWithKey:key andParent:nil];
} else {
AVLTreeNode *n = self.root;
AVLTreeNode *parent;
while (true) {
if (n.key == key) {
... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #Logo | Logo | to mean_angle :angles
local "avgsin
make "avgsin quotient apply "sum map "sin :angles count :angles
local "avgcos
make "avgcos quotient apply "sum map "cos :angles count :angles
output (arctan :avgcos :avgsin)
end
foreach [[350 10] [90 180 270 360] [10 20 30]] [
print (sentence [The average of \(] ? ... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #Lua | Lua | function meanAngle (angleList)
local sumSin, sumCos = 0, 0
for i, angle in pairs(angleList) do
sumSin = sumSin + math.sin(math.rad(angle))
sumCos = sumCos + math.cos(math.rad(angle))
end
local result = math.deg(math.atan2(sumSin, sumCos))
return string.format("%.2f", result)
end
print(meanAngle({350... |
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #Elena | Elena | import system'routines;
import system'math;
import extensions;
extension op
{
get Median()
{
var sorted := self.ascendant();
var len := sorted.Length;
if (len == 0)
{
^ nil
}
else
{
var middleIndex := len / 2;
if ... |
http://rosettacode.org/wiki/Averages/Median | Averages/Median | Task[edit]
Write a program to find the median value of a vector of floating-point numbers.
The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements. In that case, return the average of the two middle values.
There are several approaches ... | #Elixir | Elixir | defmodule Average do
def median([]), do: nil
def median(list) do
len = length(list)
sorted = Enum.sort(list)
mid = div(len, 2)
if rem(len,2) == 0, do: (Enum.at(sorted, mid-1) + Enum.at(sorted, mid)) / 2,
else: Enum.at(sorted, mid)
end
end
median = fn list -> IO.puts "#{ins... |
http://rosettacode.org/wiki/Averages/Pythagorean_means | Averages/Pythagorean means | Task[edit]
Compute all three of the Pythagorean means of the set of integers 1 through 10 (inclusive).
Show that
A
(
x
1
,
…
,
x
n
)
≥
G
(
x
1
,
…
,
x
n
)
≥
H
(
x
1
,
…
,
x
n
)
{\displaystyle A(x_{1},\ldots ,x_{n})\geq G(x_{1},\ldots ,x_{n})\geq H(x_{1},\ldots ,x_{n})}
for this set of p... | #IS-BASIC | IS-BASIC | 100 PROGRAM "Averages.bas"
110 NUMERIC ARR(1 TO 10)
120 FOR I=LBOUND(ARR) TO UBOUND(ARR)
130 LET ARR(I)=I
140 NEXT
150 PRINT "Arithmetic mean =";ARITHM(ARR)
160 PRINT "Geometric mean =";GEOMETRIC(ARR)
170 PRINT "Harmonic mean =";HARMONIC(ARR)
180 DEF ARITHM(REF A)
190 LET T=0
200 FOR I=LBOUND(A) TO UBOUND(A)
2... |
http://rosettacode.org/wiki/Balanced_ternary | Balanced ternary | Balanced ternary is a way of representing numbers. Unlike the prevailing binary representation, a balanced ternary integer is in base 3, and each digit can have the values 1, 0, or −1.
Examples
Decimal 11 = 32 + 31 − 30, thus it can be written as "++−"
Decimal 6 = 32 − 31 + 0 × 30, thus it can be written as "+−0"
... | #Perl | Perl | use strict;
use warnings;
my @d = qw( 0 + - );
my @v = qw( 0 1 -1 );
sub to_bt {
my $n = shift;
my $b = '';
while( $n ) {
my $r = $n%3;
$b .= $d[$r];
$n -= $v[$r];
$n /= 3;
}
return scalar reverse $b;
}
sub from_bt {
my $n = 0;
for( split //, shift ) { # Horner
... |
http://rosettacode.org/wiki/Babbage_problem | Babbage problem |
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example:
What is the smallest positive integer whose square ends in the digits 269,696?
— Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p.... | #PureBasic | PureBasic | EnableExplicit
Macro putresult(n)
If OpenConsole("Babbage_problem")
PrintN("The smallest number whose square ends in 269696 is " + Str(n))
Input()
EndIf
EndMacro
CompilerIf #PB_Processor_x64
#MAXINT = 1 << 63 - 1
CompilerElseIf #PB_Processor_x86
#MAXINT = 1 << 31 - 1
CompilerEndIf
#GOAL = 269696
#... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #jq | jq | # Return whether the two numbers `a` and `b` are close.
# Closeness is determined by the `epsilon` parameter -
# the numbers are considered close if the difference between them
# is no more than epsilon * max(abs(a), abs(b)).
def isclose(a; b; epsilon):
((a - b) | fabs) <= (([(a|fabs), (b|fabs)] | max) * epsilon);
... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Julia | Julia | testvalues = [[100000000000000.01, 100000000000000.011],
[100.01, 100.011],
[10000000000000.001 / 10000.0, 1000000000.0000001000],
[0.001, 0.0010000001],
[0.000000000000000000000101, 0.0],
[sqr... |
http://rosettacode.org/wiki/Approximate_equality | Approximate equality | Sometimes, when testing whether the solution to a task (for example, here on Rosetta Code) is correct, the
difference in floating point calculations between different language implementations becomes significant.
For example, a difference between 32 bit and 64 bit floating point calculations may appear by
about the 8t... | #Kotlin | Kotlin | import kotlin.math.abs
import kotlin.math.sqrt
fun approxEquals(value: Double, other: Double, epsilon: Double): Boolean {
return abs(value - other) < epsilon
}
fun test(a: Double, b: Double) {
val epsilon = 1e-18
println("$a, $b => ${approxEquals(a, b, epsilon)}")
}
fun main() {
test(1000000000000... |
http://rosettacode.org/wiki/Balanced_brackets | Balanced brackets | Task:
Generate a string with N opening brackets [ and with N closing brackets ], in some arbitrary order.
Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples
(empty) ... | #CoffeeScript | CoffeeScript |
isBalanced = (brackets) ->
openCount = 0
for bracket in brackets
openCount += if bracket is '[' then 1 else -1
return false if openCount < 0
openCount is 0
bracketsCombinations = (n) ->
for i in [0...Math.pow 2, n]
str = i.toString 2
str = '0' + str while str.length < n
str.replace(/0/g,... |
http://rosettacode.org/wiki/Append_a_record_to_the_end_of_a_text_file | Append a record to the end of a text file | Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment.
This feature is most useful in the case of log files,... | #C.2B.2B | C++ | #include <iostream>
#include <fstream>
#include <string>
#include <vector>
std::ostream& operator<<(std::ostream& out, const std::string s) {
return out << s.c_str();
}
struct gecos_t {
std::string fullname, office, extension, homephone, email;
friend std::ostream& operator<<(std::ostream&, const geco... |
http://rosettacode.org/wiki/Associative_array/Creation | Associative array/Creation | Task
The goal is to create an associative array (also known as a dictionary, map, or hash).
Related tasks:
Associative arrays/Iteration
Hash from two arrays
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element ins... | #ALGOL_68 | ALGOL 68 | main:(
MODE COLOR = BITS;
FORMAT color repr = $"16r"16r6d$;
# This is an associative array which maps strings to ints #
MODE ITEM = STRUCT(STRING key, COLOR value);
REF[]ITEM color map items := LOC[0]ITEM;
PROC color map find = (STRING color)REF COLOR:(
REF COLOR out;
# linear search! #
FOR in... |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #ALGOL_W | ALGOL W | begin
% find some anti-primes - numbers with more factors than the numbers %
% smaller than them %
% calculates the number of divisors of v %
integer procedure divisor_count( integer value v ) ; begin
integer t... |
http://rosettacode.org/wiki/Anti-primes | Anti-primes | The anti-primes
(or highly composite numbers, sequence A002182 in the OEIS)
are the natural numbers with more factors than any smaller than itself.
Task
Generate and show here, the first twenty anti-primes.
Related tasks
Factors of an integer
Sieve of Eratosthenes
| #AppleScript | AppleScript | on factorCount(n)
set counter to 0
set sqrt to n ^ 0.5
set limit to sqrt div 1
if (limit = sqrt) then
set counter to counter + 1
set limit to limit - 1
end if
repeat with i from limit to 1 by -1
if (n mod i is 0) then set counter to counter + 2
end repeat
return... |
http://rosettacode.org/wiki/Atomic_updates | Atomic updates |
Task
Define a data type consisting of a fixed number of 'buckets', each containing a nonnegative integer value, which supports operations to:
get the current value of any bucket
remove a specified amount from one specified bucket and add it to another, preserving the total of all bucket values, and clamping the t... | #Groovy | Groovy | class Buckets {
def cells = []
final n
Buckets(n, limit=1000, random=new Random()) {
this.n = n
(0..<n).each {
cells << random.nextInt(limit)
}
}
synchronized getAt(i) {
cells[i]
}
synchronized transfer(from, to, amount) {
assert fr... |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Emacs_Lisp | Emacs Lisp | (require 'cl-lib)
(let ((x 41))
(cl-assert (= x 42) t "This shouldn't happen")) |
http://rosettacode.org/wiki/Assertions | Assertions | Assertions are a way of breaking out of code when there is an error or an unexpected input.
Some languages throw exceptions and some treat it as a break point.
Task
Show an assertion in your language by asserting that an integer variable is equal to 42.
| #Erlang | Erlang | 1> N = 42.
42
2> N = 43.
** exception error: no match of right hand side value 43
3> N = 42.
42
4> 44 = N.
** exception error: no match of right hand side value 42
5> 42 = N.
42 |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #ALGOL_W | ALGOL W | begin
procedure printSquare ( integer value x ) ; writeon( i_w := 1, s_w := 0, " ", x * x );
% applys f to each element of a from lb to ub (inclusive) %
procedure applyI ( procedure f; integer array a ( * ); integer value lb, ub ) ;
for i := lb until ub do f( a( i ) );
% test applyI %
begin
... |
http://rosettacode.org/wiki/Apply_a_callback_to_an_array | Apply a callback to an array | Task
Take a combined set of elements and apply a function to each element.
| #APL | APL | - 1 2 3
¯1 ¯2 ¯3
2 * 1 2 3 4
2 4 8 16
2 × ⍳4
2 4 6 8
3 * 3 3 ⍴ ⍳9
3 9 27
81 243 729
2187 6561 19683
|
http://rosettacode.org/wiki/Averages/Mode | Averages/Mode | Task[edit]
Write a program to find the mode value of a collection.
The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriat... | #MUMPS | MUMPS | MODE(X)
;X is assumed to be a list of numbers separated by "^"
;I is a loop index
;L is the length of X
;Y is a new array
;ML is the list of modes
;LOC is a placeholder to shorten the statement
Q:'$DATA(X) "No data"
Q:X="" "Empty Set"
NEW Y,I,L,LOC
SET L=$LENGTH(X,"^"),ML=""
FOR I=1:1:L SET LOC=+$P(X,"^",I),... |
http://rosettacode.org/wiki/Associative_array/Iteration | Associative array/Iteration | Show how to iterate over the key-value pairs of an associative array, and print each pair out.
Also show how to iterate just over the keys, or the values, if there is a separate way to do that in your language.
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked ... | #C | C | using System;
using System.Collections.Generic;
namespace AssocArrays
{
class Program
{
static void Main(string[] args)
{
Dictionary<string,int> assocArray = new Dictionary<string,int>();
assocArray["Hello"] = 1;
assocArray.Add("World", 2);
a... |
http://rosettacode.org/wiki/Apply_a_digital_filter_(direct_form_II_transposed) | Apply a digital filter (direct form II transposed) | Digital filters are used to apply a mathematical operation to a sampled signal. One of the common formulations is the "direct form II transposed" which can represent both infinite impulse response (IIR) and finite impulse response (FIR) filters, as well as being more numerically stable than other forms. [1]
Task
Filt... | #Go | Go | package main
import "fmt"
type filter struct {
b, a []float64
}
func (f filter) filter(in []float64) []float64 {
out := make([]float64, len(in))
s := 1. / f.a[0]
for i := range in {
tmp := 0.
b := f.b
if i+1 < len(b) {
b = b[:i+1]
}
for j, bj := ... |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #Chef | Chef | Mean.
Chef has no way to detect EOF, so rather than interpreting
some arbitrary number as meaning "end of input", this program
expects the first input to be the sample size. Pass in the samples
themselves as the other inputs. For example, if you wanted to
compute the mean of 10, 100, 47, you could pass in 3, 10, 100,... |
http://rosettacode.org/wiki/Averages/Arithmetic_mean | Averages/Arithmetic mean | Task[edit]
Write a program to find the mean (arithmetic average) of a numeric vector.
In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin... | #Clojure | Clojure | (defn mean [sq]
(if (empty? sq)
0
(/ (reduce + sq) (count sq)))) |
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Ol | Ol |
(define a1 {
'name "Rocket Skates"
'price 12.75
'color "yellow"
})
(define a2 {
'price 15.25
'color "red"
'year 1974
})
(print "a1: " a1)
(print "a2: " a2)
(define (collide a b) b) ; will use new key value
(print "merged a1 a2: " (ff-union collide a1 a2))
|
http://rosettacode.org/wiki/Associative_array/Merging | Associative array/Merging | Task
Define two associative arrays, where one represents the following "base" data:
Key
Value
"name"
"Rocket Skates"
"price"
12.75
"color"
"yellow"
And the other represents "update" data:
Key
Value
"price"
15.25
"color"
"red"
"year"
1974
Merge these into a new associativ... | #Perl | Perl | use strict;
use warnings;
my %base = ("name" => "Rocket Skates", "price" => 12.75, "color" => "yellow");
my %more = ("price" => 15.25, "color" => "red", "year" => 1974);
print "Update\n";
my %update = (%base, %more);
printf "%-7s %s\n", $_, $update{$_} for sort keys %update;
print "\nMerge\n";
my %merge;
$merge{$... |
http://rosettacode.org/wiki/Average_loop_length | Average loop length | Let f be a uniformly-randomly chosen mapping from the numbers 1..N to the numbers 1..N (note: not necessarily a permutation of 1..N; the mapping could produce a number in more than one way or not at all). At some point, the sequence 1, f(1), f(f(1))... will contain a repetition, a number that occurring for the second t... | #Phix | Phix | constant MAX = 20,
ITER = 1000000
function expected(integer n)
atom sum = 0
for i=1 to n do
sum += factorial(n) / power(n,i) / factorial(n-i)
end for
return sum
end function
function test(integer n)
integer count = 0, x, bits
for i=1 to ITER do
x = 1
bits = 0
... |
http://rosettacode.org/wiki/Averages/Simple_moving_average | Averages/Simple moving average | Computing the simple moving average of a series of numbers.
Task[edit]
Create a stateful function/class/instance that takes a period and returns a routine that takes a number as argument and returns a simple moving average of its arguments so far.
Description
A simple moving average is a method for computing an avera... | #Ruby | Ruby | def simple_moving_average(size)
nums = []
sum = 0.0
lambda do |hello|
nums << hello
goodbye = nums.length > size ? nums.shift : 0
sum += hello - goodbye
sum / nums.length
end
end
ma3 = simple_moving_average(3)
ma5 = simple_moving_average(5)
(1.upto(5).to_a + 5.downto(1).to_a).each do |num|
... |
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Haskell | Haskell | import Data.Numbers.Primes
import Data.Bool (bool)
attractiveNumbers :: [Integer]
attractiveNumbers =
[1 ..] >>= (bool [] . return) <*> (isPrime . length . primeFactors)
main :: IO ()
main = print $ takeWhile (<= 120) attractiveNumbers |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #Nim | Nim | import math, complex, strutils, sequtils
proc meanAngle(deg: openArray[float]): float =
var c: Complex[float]
for d in deg:
c += rect(1.0, degToRad(d))
radToDeg(phase(c / float(deg.len)))
proc meanTime(times: openArray[string]): string =
const day = 24 * 60 * 60
let
angles = times.map(proc(time: s... |
Subsets and Splits
Rosetta Code COBOL Python Hard Tasks
Identifies and retrieves challenging tasks that exist in both COBOL and Python, revealing cross-language programming patterns and difficulty levels for comparative analysis.
Rosetta Code Task Comparisons
Identifies tasks common to both COBOL and Python languages that are described as having difficulty levels, revealing cross-language task similarities and providing useful comparative programming examples.
Select Specific Languages Codes
Retrieves specific programming language names and codes from training data, providing basic filtering but limited analytical value beyond identifying these particular languages.