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/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... | #Python | Python | from __future__ import division # Only necessary for Python 2.X
from math import factorial
from random import randrange
MAX_N = 20
TIMES = 1000000
def analytical(n):
return sum(factorial(n) / pow(n, i) / factorial(n -i) for i in range(1, n+1))
def test(n, times):
count = 0
for i in range(times):
... |
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... | #R | R |
expected <- function(size) {
result <- 0
for (i in 1:size) {
result <- result + factorial(size) / size^i / factorial(size -i)
}
result
}
knuth <- function(size) {
v <- sample(1:size, size, replace = TRUE)
visit <- vector('logical',size)
place <- 1
visit[[1]] <- TRUE
steps <- 0
repeat {
... |
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... | #Scala | Scala | class MovingAverage(period: Int) {
private var queue = new scala.collection.mutable.Queue[Double]()
def apply(n: Double) = {
queue.enqueue(n)
if (queue.size > period)
queue.dequeue
queue.sum / queue.size
}
override def toString = queue.mkString("(", ", ", ")")+", period "+period+", average "+(... |
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.... | #jq | jq |
def count(s): reduce s as $x (null; .+1);
def is_attractive:
count(prime_factors) | is_prime;
def printattractive($m; $n):
"The attractive numbers from \($m) to \($n) are:\n",
[range($m; $n+1) | select(is_attractive)];
printattractive(1; 120) |
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.... | #Julia | Julia | using Primes
# oneliner is println("The attractive numbers from 1 to 120 are:\n", filter(x -> isprime(sum(values(factor(x)))), 1:120))
isattractive(n) = isprime(sum(values(factor(n))))
printattractive(m, n) = println("The attractive numbers from $m to $n are:\n", filter(isattractive, m:n))
printattractive(1, 12... |
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 ... | #PARI.2FGP | PARI/GP | meanAngle(v)=atan(sum(i=1,#v,sin(v[i]))/sum(i=1,#v,cos(v[i])))%(2*Pi)
meanTime(v)=my(x=meanAngle(2*Pi*apply(u->u[1]/24+u[2]/1440+u[3]/86400, v))*12/Pi); [x\1, 60*(x-=x\1)\1, round(60*(60*x-60*x\1))]
meanTime([[23,0,17], [23,40,20], [0,12,45], [0,17,19]]) |
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.... | #Raku | Raku |
class AVL-Tree {
has $.root is rw = 0;
class Node {
has $.key is rw = '';
has $.parent is rw = 0;
has $.data is rw = 0;
has $.left is rw = 0;
has $.right is rw = 0;
has Int $.balance is rw = 0;
has Int $.height is rw = 0;
}
#========... |
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 ... | #OCaml | OCaml | let pi = 3.14159_26535_89793_23846_2643
let deg2rad d =
d *. pi /. 180.0
let rad2deg r =
r *. 180.0 /. pi
let mean_angle angles =
let rad_angles = List.map deg2rad angles in
let sum_sin = List.fold_left (fun sum a -> sum +. sin a) 0.0 rad_angles
and sum_cos = List.fold_left (fun sum a -> sum +. cos a) 0... |
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 ... | #ooRexx | ooRexx | /*REXX program computes the mean angle (angles expressed in degrees). */
numeric digits 50 /*use fifty digits of precision, */
showDig=10 /*··· but only display 10 digits.*/
xl = 350 10 ; say showit(xl, meanAngleD(xl) )
xl = 90 180 270 360 ; say... |
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 ... | #Excel | Excel |
=MEDIAN(A1:A10)
|
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 ... | #F.23 | F# |
let rec splitToFives list =
match list with
| a::b::c::d::e::tail ->
([a;b;c;d;e])::(splitToFives tail)
| [] -> []
| _ ->
let left = 5 - List.length (list)
let last = List.append list (List.init left (fun _ -> System.Double.PositiveInfinity) )
... |
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... | #jq | jq | def amean: add/length;
def logProduct: map(log) | add;
def gmean: (logProduct / length) | exp;
def hmean: length / (map(1/.) | add);
# Tasks:
[range(1;11) ] | [amean, gmean, hmean] as $ans
| ( $ans[],
"amean > gmean > hmean => \($ans[0] > $ans[1] and $ans[1] > $ans[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"
... | #Python | Python | class BalancedTernary:
# Represented as a list of 0, 1 or -1s, with least significant digit first.
str2dig = {'+': 1, '-': -1, '0': 0} # immutable
dig2str = {1: '+', -1: '-', 0: '0'} # immutable
table = ((0, -1), (1, -1), (-1, 0), (0, 0), (1, 0), (-1, 1), (0, 1)) # immutable
def __init__(self, i... |
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.... | #Red | Red | Red []
number: 510 ;; starting number
;; repeat, until the last condition in the block is true
until [
number: number + 2 ;; only even numbers can have even squares
;; The word modulo computes the non-negative remainder of the
;; first argument divided by the second argument.
;; ** => Returns a number raised to ... |
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.... | #REXX | REXX | /*REXX program finds the lowest (positive) integer whose square ends in 269,696. */
do j=2 by 2 until right(j * j, 6) == 269696 /*start J at two, increment by two. */
end /*◄── signifies the end of the DO loop.*/
... |
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... | #Perl | Perl | use strict;
use warnings;
sub is_close {
my($a,$b,$eps) = @_;
$eps //= 15;
my $epse = $eps;
$epse++ if sprintf("%.${eps}f",$a) =~ /\./;
$epse++ if sprintf("%.${eps}f",$a) =~ /\-/;
my $afmt = substr((sprintf "%.${eps}f", $a), 0, $epse);
my $bfmt = substr((sprintf "%.${eps}f", $b), 0, $epse)... |
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) ... | #D | D | import std.stdio, std.algorithm, std.random, std.range;
void main() {
foreach (immutable i; 1 .. 9) {
immutable s = iota(i * 2).map!(_ => "[]"[uniform(0, 2)]).array;
writeln(s.balancedParens('[', ']') ? " OK: " : "bad: ", s);
}
} |
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,... | #Elixir | Elixir |
defmodule Gecos do
defstruct [:fullname, :office, :extension, :homephone, :email]
defimpl String.Chars do
def to_string(gecos) do
[:fullname, :office, :extension, :homephone, :email]
|> Enum.map_join(",", &Map.get(gecos, &1))
end
end
end
defmodule Passwd do
defstruct [:account, :passwo... |
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,... | #Fortran | Fortran | PROGRAM DEMO !As per the described task, more or less.
TYPE DETAILS !Define a component.
CHARACTER*28 FULLNAME
CHARACTER*12 OFFICE
CHARACTER*16 EXTENSION
CHARACTER*16 HOMEPHONE
CHARACTER*88 EMAIL
END TYPE DETAILS
TYPE USERSTUFF !Define the desired data aggreg... |
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... | #ARM_Assembly | ARM Assembly |
/* ARM assembly Raspberry PI or android 32 bits */
/* program hashmap.s */
/* */
/* REMARK 1 : this program use routines in a include file
see task Include a file language arm assembly
for the routine affichageMess conversion10
see at end of this program the instruction include */
/* for con... |
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
| #BCPL | BCPL | get "libhdr"
manifest $( LIMIT = 20 $)
let nfactors(n) =
n < 2 -> 1, valof
$( let c = 2
for i=2 to n/2
if n rem i = 0 then c := c + 1
resultis c
$)
let start() be
$( let max = 0 and seen = 0 and n = 1
while seen < LIMIT
$( let f = nfactors(n)
if f > max
$( writef("%N ... |
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
| #C | C | #include <stdio.h>
int countDivisors(int n) {
int i, count;
if (n < 2) return 1;
count = 2; // 1 and n
for (i = 2; i <= n/2; ++i) {
if (n%i == 0) ++count;
}
return count;
}
int main() {
int n, d, maxDiv = 0, count = 0;
printf("The first 20 anti-primes are:\n");
for (n = 1... |
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... | #Julia | Julia | using StatsBase
function runall()
nbuckets = 16
unfinish = true
spinner = ReentrantLock()
buckets = rand(1:99, nbuckets)
totaltrans = 0
bucketsum() = sum(buckets)
smallpause() = sleep(rand() / 2000)
picktwo() = (samplepair(nbuckets)...)
function equalizer()
while unfinish... |
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... | #Kotlin | Kotlin | // version 1.2.0
import java.util.concurrent.ThreadLocalRandom
import kotlin.concurrent.thread
const val NUM_BUCKETS = 10
class Buckets(data: IntArray) {
private val data = data.copyOf()
operator fun get(index: Int) = synchronized(data) { data[index] }
fun transfer(srcIndex: Int, dstIndex: Int, am... |
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.
| #Haskell | Haskell | import Control.Exception
main = let a = someValue in
assert (a == 42) -- throws AssertionFailed when a is not 42
somethingElse -- what to return when a is 42 |
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.
| #Icon_and_Unicon | Icon and Unicon | ...
runerr(n,( expression ,"Assertion/error - message.")) # Throw (and possibly trap) an error number n if expression succeeds.
...
stop(( expression ,"Assertion/stop - message.")) # Terminate program if expression succeeds.
... |
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.
| #J | J | assert 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.
| #Bracmat | Bracmat | ( ( callbackFunction1
= location value
. !arg:(?location,?value)
& out$(str$(array[ !location "] = " !!value))
)
& ( callbackFunction2
= location value
. !arg:(?location,?value)
& !!value^2:?!value
)
& ( mapar
= arr len callback i
. !arg:(?arr,?len,?callback)
& 0:?i
... |
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.
| #Brat | Brat | #Print out each element in array
[:a :b :c :d :e].each { element |
p element
} |
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... | #Objective-C | Objective-C | #import <Foundation/Foundation.h>
@interface NSArray (Mode)
- (NSArray *)mode;
@end
@implementation NSArray (Mode)
- (NSArray *)mode {
NSCountedSet *seen = [NSCountedSet setWithArray:self];
int max = 0;
NSMutableArray *maxElems = [NSMutableArray array];
for ( obj in seen ) {
int count = [see... |
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 ... | #Clojure | Clojure |
(doseq [[k v] {:a 1, :b 2, :c 3}]
(println k "=" v))
(doseq [k (keys {:a 1, :b 2, :c 3})]
(println k))
(doseq [v (vals {:a 1, :b 2, :c 3})]
(println v))
|
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 ... | #CoffeeScript | CoffeeScript | hash =
a: 'one'
b: 'two'
for key, value of hash
console.log key, value
for key of hash
console.log key
|
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... | #Julia | Julia | function DF2TFilter(a::Vector, b::Vector, sig::Vector)
rst = zeros(sig)
for i in eachindex(sig)
tmp = sum(b[j] * sig[i-j+1] for j in 1:min(i, length(b)))
tmp -= sum(a[j] * rst[i-j+1] for j in 1:min(i, length(a)))
rst[i] = tmp / a[1]
end
return rst
end
acoef = [1.00000000, -2.7... |
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... | #Kotlin | Kotlin | // version 1.1.3
fun filter(a: DoubleArray, b: DoubleArray, signal: DoubleArray): DoubleArray {
val result = DoubleArray(signal.size)
for (i in 0 until signal.size) {
var tmp = 0.0
for (j in 0 until b.size) {
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... | #Dart | Dart | num mean(List<num> l) => l.reduce((num p, num n) => p + n) / l.length;
void main(){
print(mean([1,2,3,4,5,6,7]));
} |
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... | #dc | dc | 1 2 3 5 7 zsn1k[+z1<+]ds+xln/p
3.6 |
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... | #Ring | Ring |
load "stdlib.ring"
list1 = [:name = "Rocket Skates", :price = 12.75, :color = "yellow"]
list2 = [:price = 15.25, :color = "red", :year = 1974]
for n = 1 to len(list2)
flag = 0
for m = 1 to len(list1)
if list2[n][1] = list1[m][1]
flag = 1
del(list1,m)
add(list1,[lis... |
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... | #Ruby | Ruby | base = {"name" => "Rocket Skates", "price" => 12.75, "color" => "yellow"}
update = {"price" => 15.25, "color" => "red", "year" => 1974}
result = base.merge(update)
p result |
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... | #Rust | Rust | use std::collections::HashMap;
fn main() {
let mut original = HashMap::new();
original.insert("name", "Rocket Skates");
original.insert("price", "12.75");
original.insert("color", "yellow");
let mut update = HashMap::new();
update.insert("price", "15.25");
update.insert("color", "red");
... |
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... | #Scheme | Scheme | ; Merge alists by appending the update list onto the front of the base list.
; (The extra '() is so that append doesn't co-opt the second list.)
(define append-alists
(lambda (base update)
(append update base '())))
; Test...
(printf "~%Merge using append procedure...~%")
; The original base and update alists.
... |
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... | #Racket | Racket |
#lang racket
(require (only-in math factorial))
(define (analytical n)
(for/sum ([i (in-range 1 (add1 n))])
(/ (factorial n) (expt n i) (factorial (- n i)))))
(define (test n times)
(define (count-times seen times)
(define x (random n))
(if (memq x seen) times (count-times (cons x seen) (add1 time... |
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... | #Raku | Raku | constant MAX_N = 20;
constant TRIALS = 100;
for 1 .. MAX_N -> $N {
my $empiric = TRIALS R/ [+] find-loop(random-mapping($N)).elems xx TRIALS;
my $theoric = [+]
map -> $k { $N ** ($k + 1) R/ [*] flat $k**2, $N - $k + 1 .. $N }, 1 .. $N;
FIRST say " N empiric theoric (error)";
FI... |
http://rosettacode.org/wiki/Averages/Simple_moving_average | Averages/Simple moving average | Computing the simple moving average of a series of numbers.
Task[edit]
Create a stateful function/class/instance that takes a period and returns a routine that takes a number as argument and returns a simple moving average of its arguments so far.
Description
A simple moving average is a method for computing an avera... | #Scheme | Scheme | (define ((simple-moving-averager size . nums) num)
(set! nums (cons num (if (= (length nums) size) (reverse (cdr (reverse nums))) nums)))
(/ (apply + nums) (length nums)))
(define av (simple-moving-averager 3))
(map av '(1 2 3 4 5 5 4 3 2 1))
|
http://rosettacode.org/wiki/Attractive_numbers | Attractive numbers | A number is an attractive number if the number of its prime factors (whether distinct or not) is also prime.
Example
The number 20, whose prime decomposition is 2 × 2 × 5, is an attractive number because the number of its prime factors (3) is also prime.
Task
Show sequence items up to 120.... | #Kotlin | Kotlin | // Version 1.3.21
const val MAX = 120
fun isPrime(n: Int) : Boolean {
if (n < 2) return false
if (n % 2 == 0) return n == 2
if (n % 3 == 0) return n == 3
var d : Int = 5
while (d * d <= n) {
if (n % d == 0) return false
d += 2
if (n % d == 0) return false
d += 4
... |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #Perl | Perl | use strict;
use warnings;
use POSIX 'fmod';
use Math::Complex;
use List::Util qw(sum);
use utf8;
use constant τ => 2 * 3.1415926535;
# time-of-day to radians
sub tod2rad {
($h,$m,$s) = split /:/, @_[0];
(3600*$h + 60*$m + $s) * τ / 86400;
}
# radians to time-of-day
sub rad2tod {
my $x = $_[0] * 86400 ... |
http://rosettacode.org/wiki/AVL_tree | AVL tree |
This page uses content from Wikipedia. The original article was at AVL tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In computer science, an AVL tree is a self-balancing binary search tree.... | #Rust | Rust | import scala.collection.mutable
class AVLTree[A](implicit val ordering: Ordering[A]) extends mutable.SortedSet[A] {
if (ordering eq null) throw new NullPointerException("ordering must not be null")
private var _root: AVLNode = _
private var _size = 0
override def size: Int = _size
override def forea... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #PARI.2FGP | PARI/GP | meanAngle(v)=atan(sum(i=1,#v,sin(v[i]))/sum(i=1,#v,cos(v[i])))%(2*Pi)
meanDegrees(v)=meanAngle(v*Pi/180)*180/Pi
apply(meanDegrees,[[350, 10], [90, 180, 270, 360], [10, 20, 30]]) |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #Pascal | Pascal | program MeanAngle;
{$IFDEF DELPHI}
{$APPTYPE CONSOLE}
{$ENDIF}
uses
math;// sincos and atan2
type
tAngles = array of double;
function MeanAngle(const a:tAngles;cnt:longInt):double;
// calculates mean angle.
// returns 0.0 if direction is not sure.
const
eps = 1e-10;
var
i : LongInt;
s,c,
Sumsin,SumCos... |
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 ... | #Factor | Factor | USING: arrays kernel locals math math.functions random sequences ;
IN: median
: pivot ( seq -- pivot ) random ;
: split ( seq pivot -- {lt,eq,gt} )
[ [ < ] curry partition ] keep
[ = ] curry partition
3array ;
DEFER: nth-in-order
:: nth-in-order-recur ( seq ind -- elt )
seq dup pivot split
dup [ length ... |
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 ... | #Forth | Forth | -1 cells constant -cell
: cell- -cell + ;
defer lessthan ( a@ b@ -- ? ) ' < is lessthan
: mid ( l r -- mid ) over - 2/ -cell and + ;
: exch ( addr1 addr2 -- ) dup @ >r over @ swap ! r> swap ! ;
: part ( l r -- l r r2 l2 )
2dup mid @ >r ( r: pivot )
2dup begin
swap begin dup @ r@ lessthan while cell... |
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... | #Julia | Julia | amean(A) = sum(A)/length(A)
gmean(A) = prod(A)^(1/length(A))
hmean(A) = length(A)/sum(1./A) |
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"
... | #Racket | Racket | #lang racket
;; Represent a balanced-ternary number as a list of 0's, 1's and -1's.
;;
;; e.g. 11 = 3^2 + 3^1 - 3^0 ~ "++-" ~ '(-1 1 1)
;; 6 = 3^2 - 3^1 ~ "+-0" ~ '(0 -1 1)
;;
;; Note: the list-rep starts with the least signifcant tert, while
;; the string-rep starts with the most significsnt tert.
... |
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.... | #Ring | Ring |
n = 0
while pow(n,2) % 1000000 != 269696
n = n + 1
end
see "The smallest number whose square ends in 269696 is : " + n + nl
see "Its square is : " + pow(n,2)
|
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.... | #Ruby | Ruby | n = 0
n = n + 2 until (n*n).modulo(1000000) == 269696
print n
|
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... | #Phix | Phix | with javascript_semantics
procedure test(atom a,b, string dfmt="%g", cfmt="%g")
string ca = sprintf(cfmt,a),
cb = sprintf(cfmt,b),
eqs = iff(ca=cb?"":"NOT "),
da = sprintf(dfmt,a),
db = sprintf(dfmt,b)
printf(1,"%30s and\n%30s are %sapproximately equal\n",{da,db,eqs})... |
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... | #Python | Python | math.isclose -> bool
a: double
b: double
*
rel_tol: double = 1e-09
maximum difference for being considered "close", relative to the
magnitude of the input values
abs_tol: double = 0.0
maximum difference for being considered "close", regardless of the
magnitude of the ... |
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) ... | #Delphi | Delphi | procedure Balanced_Brackets;
var BracketsStr : string;
TmpStr : string;
I,J : integer;
begin
Randomize;
for I := 1 to 9 do
begin
{ Create a random string of 2*N chars with N*"[" and N*"]" }
TmpStr := '';
for J := 1 to I do
TmpStr := '['+TmpStr+']';
... |
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,... | #FreeBASIC | FreeBASIC | ' FB 1.05.0 Win64
Type Person
As String fullname
As String office
As String extension
As String homephone
As String email
Declare Constructor()
Declare Constructor(As String, As String, As String, As String, As String)
Declare Operator Cast() As String
End Type
Constructor Person()
End Construc... |
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... | #Arturo | Arturo | ; create a dictionary
d: #[
name: "john"
surname: "doe"
age: 34
]
print d |
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
| #C.23 | C# | using System;
using System.Linq;
using System.Collections.Generic;
public static class Program
{
public static void Main() =>
Console.WriteLine(string.Join(" ", FindAntiPrimes().Take(20)));
static IEnumerable<int> FindAntiPrimes() {
int max = 0;
for (int i = 1; ; i++) {
i... |
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
| #C.2B.2B | C++ | #include <iostream>
int countDivisors(int n) {
if (n < 2) return 1;
int count = 2; // 1 and n
for (int i = 2; i <= n/2; ++i) {
if (n%i == 0) ++count;
}
return count;
}
int main() {
int maxDiv = 0, count = 0;
std::cout << "The first 20 anti-primes are:" << std::endl;
for (int ... |
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... | #Lasso | Lasso | define atomic => thread {
data
private buckets = staticarray_join(10, void),
private lock = 0
public onCreate => {
loop(.buckets->size) => {
.`buckets`->get(loop_count) = math_random(0, 1000)
}
}
public buckets => .`buckets`
public bucket(index::inte... |
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... | #Logtalk | Logtalk |
:- object(buckets).
:- threaded.
:- public([start/0, start/4]).
% bucket representation
:- private(bucket_/2).
:- dynamic(bucket_/2).
% use the same mutex for all the predicates that access the buckets
:- private([bucket/2, buckets/1, transfer/3]).
:- synchronized([bucket/2, bu... |
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.
| #Java | Java | public class Assertions {
public static void main(String[] args) {
int a = 13;
// ... some real code here ...
assert a == 42;
// Throws an AssertionError when a is not 42.
assert a == 42 : "Error message";
// Throws an AssertionError when a is not 42,
... |
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.
| #JavaScript | JavaScript |
function check() {
try {
if (isNaN(answer)) throw '$answer is not a number';
if (answer != 42) throw '$answer is not 42';
}
catch(err) {
console.log(err);
answer = 42;
}
finally { console.log(answer); }
}
console.count('try'); // 1
let answer;
check();
console.count('try'); // 2
answer ... |
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.
| #C | C | #ifndef CALLBACK_H
#define CALLBACK_H
/*
* By declaring the function in a separate file, we allow
* it to be used by other source files.
*
* It also stops ICC from complaining.
*
* If you don't want to use it outside of callback.c, this
* file can be removed, provided the static keyword is prepended
* to the ... |
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.
| #C.23 | C# | int[] intArray = { 1, 2, 3, 4, 5 };
// Simplest method: LINQ, functional
int[] squares1 = intArray.Select(x => x * x).ToArray();
// Slightly fancier: LINQ, query expression
int[] squares2 = (from x in intArray
select x * x).ToArray();
// Or, if you only want to call a function on each element, ju... |
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... | #OCaml | OCaml | let mode lst =
let seen = Hashtbl.create 42 in
List.iter (fun x ->
let old = if Hashtbl.mem seen x then
Hashtbl.find seen x
else 0 in
Hashtbl.replace seen x (old + 1))
lst;
let best = Hashtbl.fold (fun _ -> max) seen 0 in
Hash... |
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 ... | #Common_Lisp | Common Lisp | ;; iterate using dolist, destructure manually
(dolist (pair alist)
(destructuring-bind (key . value) pair
(format t "~&Key: ~a, Value: ~a." key value)))
;; iterate and destructure with loop
(loop for (key . value) in alist
do (format t "~&Key: ~a, Value: ~a." key value)) |
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 ... | #Crystal | Crystal | dict = {'A' => 1, 'B' => 2}
dict.each { |pair|
puts pair
}
dict.each_key { |key|
puts key
}
dict.each_value { |value|
puts value
} |
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... | #Lua | Lua | function filter(b,a,input)
local out = {}
for i=1,table.getn(input) do
local tmp = 0
local j = 0
out[i] = 0
for j=1,table.getn(b) do
if i - j < 0 then
--continue
else
tmp = tmp + b[j] * input[i - j + 1]
end
... |
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... | #Delphi | Delphi | program AveragesArithmeticMean;
{$APPTYPE CONSOLE}
uses Types;
function ArithmeticMean(aArray: TDoubleDynArray): Double;
var
lValue: Double;
begin
Result := 0;
for lValue in aArray do
Result := Result + lValue;
if Result > 0 then
Result := Result / Length(aArray);
end;
begin
Writeln(Mean(TDo... |
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... | #SenseTalk | SenseTalk | set base to {name:"Rocket Skates", price:12.75, color:"yellow"}
set update to {price:15.25, color:"red", year:1974}
put "Base data: " & base
put "Update data: " & update
// replacing as an operator, to generate merged data on the fly:
put "Merged data: " & base replacing properties in update
// replace as a com... |
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... | #Smalltalk | Smalltalk | base := Dictionary withAssociations:{
'name'-> 'Rocket Skates' .
'price' -> 12.75 .
'color' -> 'yellow' }.
update := Dictionary withAssociations:{
'price' -> 15.25 .
'color' -> 'red' .
'year' -> 1974 }.
result := Dictionary new
declareAllFrom:base;... |
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... | #Swift | Swift | let base : [String: Any] = ["name": "Rocket Skates", "price": 12.75, "color": "yellow"]
let update : [String: Any] = ["price": 15.25, "color": "red", "year": 1974]
let result = base.merging(update) { (_, new) in new }
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... | #REXX | REXX | /*REXX program computes the average loop length mapping a random field 1···N ───► 1···N */
parse arg runs tests seed . /*obtain optional arguments from the CL*/
if runs =='' | runs =="," then runs = 40 /*Not specified? Then use the default.*/
if tests =='' | tests =="," then tests= 100000... |
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... | #Sidef | Sidef | func simple_moving_average(period) {
var list = []
var sum = 0
func (number) {
list.append(number)
sum += number
if (list.len > period) {
sum -= list.shift
}
(sum / list.length)
}
}
var ma3 = simple_moving_average(3)
var ma5 = simple_moving_avera... |
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.... | #LLVM | LLVM | ; This is not strictly LLVM, as it uses the C library function "printf".
; LLVM does not provide a way to print values, so the alternative would be
; to just load the string into memory, and that would be boring.
$"ATTRACTIVE_STR" = comdat any
$"FORMAT_NUMBER" = comdat any
$"NEWLINE_STR" = comdat any
@"ATTRACTIVE_S... |
http://rosettacode.org/wiki/Averages/Mean_time_of_day | Averages/Mean time of day | Task[edit]
A particular activity of bats occurs at these times of the day:
23:00:17, 23:40:20, 00:12:45, 00:17:19
Using the idea that there are twenty-four hours in a day,
which is analogous to there being 360 degrees in a circle,
map times of day to and from angles;
and using the ideas of Averages/Mean angle
compute ... | #Phix | Phix | with javascript_semantics
function MeanAngle(sequence angles)
atom x = 0, y = 0
for i=1 to length(angles) do
atom ai_rad = angles[i]*PI/180
x += cos(ai_rad)
y += sin(ai_rad)
end for
if abs(x)<1e-16 then return "not meaningful" end if
return atan2(y,x)*180/PI
end function
fu... |
http://rosettacode.org/wiki/AVL_tree | AVL tree |
This page uses content from Wikipedia. The original article was at AVL tree. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
In computer science, an AVL tree is a self-balancing binary search tree.... | #Scala | Scala | import scala.collection.mutable
class AVLTree[A](implicit val ordering: Ordering[A]) extends mutable.SortedSet[A] {
if (ordering eq null) throw new NullPointerException("ordering must not be null")
private var _root: AVLNode = _
private var _size = 0
override def size: Int = _size
override def forea... |
http://rosettacode.org/wiki/Averages/Mean_angle | Averages/Mean angle | When calculating the average or mean of an angle one has to take into account how angles wrap around so that any angle in degrees plus any integer multiple of 360 degrees is a measure of the same angle.
If one wanted an average direction of the wind over two readings where the first reading was of 350 degrees and the ... | #Perl | Perl | sub Pi () { 3.1415926535897932384626433832795028842 }
sub meanangle {
my($x, $y) = (0,0);
($x,$y) = ($x + sin($_), $y + cos($_)) for @_;
my $atan = atan2($x,$y);
$atan += 2*Pi while $atan < 0; # Ghetto fmod
$atan -= 2*Pi while $atan > 2*Pi;
$atan;
}
sub meandegrees {
meanangle( map { $_ * Pi/180 } ... |
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 ... | #Fortran | Fortran | program Median_Test
real :: a(7) = (/ 4.1, 5.6, 7.2, 1.7, 9.3, 4.4, 3.2 /), &
b(6) = (/ 4.1, 7.2, 1.7, 9.3, 4.4, 3.2 /)
print *, median(a)
print *, median(b)
contains
function median(a, found)
real, dimension(:), intent(in) :: a
! the optional found argument can... |
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... | #K | K |
am:{(+/x)%#x}
gm:{(*/x)^(%#x)}
hm:{(#x)%+/%:'x}
{(am x;gm x;hm x)} 1+!10
5.5 4.528729 3.414172
|
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"
... | #Raku | Raku | class BT {
has @.coeff;
my %co2bt = '-1' => '-', '0' => '0', '1' => '+';
my %bt2co = %co2bt.invert;
multi method new (Str $s) {
self.bless(coeff => %bt2co{$s.flip.comb});
}
multi method new (Int $i where $i >= 0) {
self.bless(coeff => carry $i.base(3).comb.reverse);
}
multi method ... |
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.... | #Run_BASIC | Run BASIC | for n = 1 to 1000000
if n^2 MOD 1000000 = 269696 then exit for
next
PRINT "The smallest number whose square ends in 269696 is "; n
PRINT "Its square is "; n^2 |
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.... | #Rust | Rust | fn main() {
let mut current = 0;
while (current * current) % 1_000_000 != 269_696 {
current += 1;
}
println!(
"The smallest number whose square ends in 269696 is {}",
current
);
} |
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... | #R | R | approxEq <- function(...) isTRUE(all.equal(...))
tests <- rbind(c(100000000000000.01, 100000000000000.011),
c(100.01, 100.011),
c(10000000000000.001 / 10000.0, 1000000000.0000001000),
c(0.001, 0.0010000001),
c(0.000000000000000000000101, 0.0),
c(sqrt(2) *... |
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... | #Racket | Racket | #lang racket
(define (≈ a b [tolerance 1e-9])
(<= (abs (/ (- a b) (max a b))) tolerance))
(define all-tests
`(([100000000000000.01 100000000000000.011]
[100.01 100.011]
[,(/ 10000000000000.001 10000.0) 1000000000.0000001000]
[0.001 0.0010000001]
[0.000000000000000000000101 0.0]
[,(* (sq... |
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) ... | #D.C3.A9j.C3.A0_Vu | Déjà Vu | matching?:
swap 0
for c in chars:
if = c "]":
++
elseif = c "[":
if not dup:
drop
return false
--
not
!. matching? ""
!. matching? "[]"
!. matching? "[][]"
!. matching? "[[][]]"
!. matching? "]["
!. matching? "][]["
!. matching? "[]][[]" |
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,... | #Free_Pascal | Free Pascal | {$mode objFPC}
{$longStrings on}
{$modeSwitch classicProcVars+}
uses
cTypes,
// for system call wrappers
unix;
const
passwdPath = '/tmp/passwd';
resourceString
advisoryLockFailed = 'Error: could not obtain advisory lock';
type
GECOS = object
fullname: string;
office: string;
extension: string;
... |
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... | #ATS | ATS | (*------------------------------------------------------------------*)
#define ATS_DYNLOADFLAG 0
#include "share/atspre_staload.hats"
(*------------------------------------------------------------------*)
(* Interface *)
(* You can put the interface in a .s... |
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
| #CLU | CLU | % Count factors
factors = proc (n: int) returns (int)
if n<2 then return(1) end
count: int := 2
for i: int in int$from_to(2, n/2) do
if n//i = 0 then count := count + 1 end
end
return(count)
end factors
% Generate antiprimes
antiprimes = iter () yields (int)
max: int := 0
n: int :=... |
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
| #COBOL | COBOL |
******************************************************************
* COBOL solution to Anti-primes challange
* The program was run on OpenCobolIDE
******************************************************************
IDENTIFICATION DIVISION.
PROGRAM-ID. ANGLE-PRIMES.
ENVIRO... |
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... | #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | transfer[bucks_, src_, dest_, n_] :=
ReplacePart[
bucks, {src -> Max[bucks[[src]] - n, 0],
dest -> bucks[[dest]] + Min[bucks[[src]], n]}];
DistributeDefinitions[transfer];
SetSharedVariable[bucks, comp];
bucks = RandomInteger[10, 20];
comp = True;
Print["Original sum: " <> IntegerString[Plus @@ bucks]];
Prin... |
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... | #Nim | Nim | import locks
import math
import os
import random
const N = 10 # Number of buckets.
const MaxInit = 99 # Maximum initial value for buckets.
var buckets: array[1..N, Natural] # Array of buckets.
var bucketLocks: array[1..N, Lock] # Array of bucket locks.
var randomLock: Lock ... |
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.
| #jq | jq | SHELL SET UNSET
sh bash (etc) export JQ_ASSERT=1 unset JQ_ASSERT
fish set -x JQ_ASSERT 1 set -u JQ_ASSERT
csh, tcsh setenv JQ_ASSERT 1 unsetenv JQ_ASSERT
Windows/DOS SET JQ_ASSERT=1 set JQ_ASSERT=
Windows: Start > Control Panel > System > Ad... |
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.
| #Julia | Julia | const x = 5
# @assert macro checks the supplied conditional expression, with the expression
# returned in the failed-assertion message
@assert x == 42
# ERROR: LoadError: AssertionError: x == 42
# Julia also has type assertions of the form, x::Type which can be appended to
# variable for type-checking at any point
... |
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.
| #Kotlin | Kotlin | fun main() {
val a = 42
assert(a == 43)
} |
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.
| #Lasso | Lasso | local(a) = 8
fail_if(
#a != 42,
error_code_runtimeAssertion,
error_msg_runtimeAssertion + ": #a is not 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.
| #C.2B.2B | C++ | #include <iostream> //cout for printing
#include <algorithm> //for_each defined here
//create the function (print the square)
void print_square(int i) {
std::cout << i*i << " ";
}
int main() {
//create the array
int ary[]={1,2,3,4,5};
//stl for_each
std::for_each(ary,ary+5,print_square);
return 0;
}
//p... |
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.