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/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Sidef | Sidef | func eq_index(nums) {
var (i, sum, sums) = (0, 0, Hash.new);
nums.each { |n|
sums{2*sum + n} := [] -> append(i++);
sum += n;
}
sums{sum} \\ [];
} |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Swift | Swift | extension Collection where Element: Numeric {
func equilibriumIndexes() -> [Index] {
guard !isEmpty else {
return []
}
let sumAll = reduce(0, +)
var ret = [Index]()
var sumLeft: Element = 0
var sumRight: Element
for i in indices {
sumRight = sumAll - sumLeft - self[i]
... |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #PowerShell | PowerShell | # EULER.PS1
$max = 250
$powers = New-Object System.Collections.ArrayList
for ($i = 0; $i -lt $max; $i++) {
$tmp = $powers.Add([Math]::Pow($i, 5))
}
for ($x0 = 1; $x0 -lt $max; $x0++) {
for ($x1 = 1; $x1 -lt $x0; $x1++) {
for ($x2 = 1; $x2 -lt $x1; $x2++) {
for ($x3 = 1; $x3 -lt $x2; $x3++) {
... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #PL.2FI | PL/I | factorial: procedure (N) returns (fixed decimal (30));
declare N fixed binary nonassignable;
declare i fixed decimal (10);
declare F fixed decimal (30);
if N < 0 then signal error;
F = 1;
do i = 2 to N;
F = F * i;
end;
return (F);
end factorial; |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #J | J | 2 | 2 3 5 7
0 1 1 1
2|2 3 5 7 + (2^89x)-1
1 0 0 0 |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Java | Java | public static boolean isEven(int i){
return (i & 1) == 0;
} |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Seed7 | Seed7 | $ include "seed7_05.s7i";
const proc: main is func
local
var integer: n is 0;
var integer: k is 0;
begin
for n range 0 to 66 do
for k range 0 to n do
write(n ! k <& " ");
end for;
writeln;
end for;
end func; |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #SequenceL | SequenceL |
choose(n, k) := product(k + 1 ... n) / product(1 ... n - k);
|
http://rosettacode.org/wiki/Emirp_primes | Emirp primes | An emirp (prime spelled backwards) are primes that when reversed (in their decimal representation) are a different prime.
(This rules out palindromic primes.)
Task
show the first twenty emirps
show all emirps between 7,700 and 8,000
show the 10,000th emirp
In each list, the numbe... | #Nim | Nim | import math
# Increments to find the next divisor when testing primality.
const Incr = [4, 2, 4, 2, 4, 6, 2, 6]
#---------------------------------------------------------------------------------------------------
func reversed(n: int): int =
## Return the reversed number in base 10 representation.
var n = n
... |
http://rosettacode.org/wiki/Emirp_primes | Emirp primes | An emirp (prime spelled backwards) are primes that when reversed (in their decimal representation) are a different prime.
(This rules out palindromic primes.)
Task
show the first twenty emirps
show all emirps between 7,700 and 8,000
show the 10,000th emirp
In each list, the numbe... | #Oforth | Oforth | : isEmirp(n)
n isPrime ifFalse: [ false return ]
n asString reverse asInteger dup n == ifTrue: [ drop false ] else: [ isPrime ] ;
: main(min, max, length)
| l |
ListBuffer new ->l
min while(l size length < ) [
dup max > ifTrue: [ break ]
dup isEmirp ifTrue: [ dup l add ] 1 +
]
drop... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #Gambas | Gambas | Public Sub Main()
Dim sString As String[] = ["", "Hello", "world", "", "Today", "Tomorrow", "", "", "End!"]
Dim sTemp As String
Dim siCount As Short
For Each sTemp In sString
If sString[siCount] Then
Print "String " & siCount & " = " & sString[siCount]
Else
Print "String " & siCount & " is empty"
End ... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #Go | Go | // define and initialize an empty string
var s string
s2 := ""
// assign an empty string to a variable
s = ""
// check that a string is empty, any of:
s == ""
len(s) == 0
// check that a string is not empty, any of:
s != ""
len(s) != 0 // or > 0 |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Erlang | Erlang | -module(empty). |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #ERRE | ERRE |
PROGRAM EMPTY
BEGIN
END PROGRAM
|
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #eSQL | eSQL | CREATE COMPUTE MODULE ESQL_Compute
CREATE FUNCTION Main() RETURNS BOOLEAN
BEGIN
RETURN TRUE;
END;
END MODULE; |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #Lua | Lua | function log2 (x) return math.log(x) / math.log(2) end
function entropy (X)
local N, count, sum, i = X:len(), {}, 0
for char = 1, N do
i = X:sub(char, char)
if count[i] then
count[i] = count[i] + 1
else
count[i] = 1
end
end
for n_i, count_i in pa... |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #F.C5.8Drmul.C3.A6 | Fōrmulæ | package main
import "fmt"
func halve(i int) int { return i/2 }
func double(i int) int { return i*2 }
func isEven(i int) bool { return i%2 == 0 }
func ethMulti(i, j int) (r int) {
for ; i > 0; i, j = halve(i), double(j) {
if !isEven(i) {
r += j
}
}
return
}
func main()... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Tcl | Tcl | proc listEquilibria {list} {
set after 0
foreach item $list {incr after $item}
set result {}
set idx 0
set before 0
foreach item $list {
incr after [expr {-$item}]
if {$after == $before} {
lappend result $idx
}
incr before $item
incr idx
}
return $result
} |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Ursala | Ursala | #import std
#import int
edex = num@yK33ySPtK33xtS2px; ~&nS+ *~ ==+ ~~r sum:-0
#cast %nL
example = edex <-7,1,5,2,-4,3,0> |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #Prolog | Prolog |
makepowers :-
retractall(pow5(_, _)),
between(1, 249, X),
Y is X * X * X * X * X,
assert(pow5(X, Y)),
fail.
makepowers.
within(A, Bx, N) :- % like between but with an exclusive upper bound
succ(B, Bx),
between(A, B, N).
solution(X0, X1, X2, X3, Y) :-
makepowers,
within(4, 250, X... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #PL.2FSQL | PL/SQL |
DECLARE
/*====================================================================================================
-- For : https://rosettacode.org/
-- --
-- Task : Factorial
-- Method : iterative
-- Language: PL/SQL
--
-- 2020-12-30 by alvalongo
================================================... |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #JavaScript | JavaScript | function isEven( i ) {
return (i & 1) === 0;
}
|
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #jq | jq | def is_even: type == "number" and floor == 0 and . % 2 == 0; |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Sidef | Sidef | func binomial(n,k) {
n! / ((n-k)! * k!)
}
say binomial(400, 200) |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Smalltalk | Smalltalk | Transcript showCR: (5 binco:3).
Transcript showCR: (400 binco:200) |
http://rosettacode.org/wiki/Emirp_primes | Emirp primes | An emirp (prime spelled backwards) are primes that when reversed (in their decimal representation) are a different prime.
(This rules out palindromic primes.)
Task
show the first twenty emirps
show all emirps between 7,700 and 8,000
show the 10,000th emirp
In each list, the numbe... | #PARI.2FGP | PARI/GP | rev(n)=subst(Polrev(digits(n)),'x,10);
emirp(n)=my(r=rev(n)); isprime(r) && isprime(n) && n!=r
select(emirp, primes(100))[1..20]
select(emirp, primes([7700,8000]))
s=10000; forprime(p=2,,if(emirp(p) && s--==0, return(p))) |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #Groovy | Groovy | def s = '' // or "" if you wish
assert s.empty
s = '1 is the loneliest number'
assert !s.empty |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #GW-BASIC | GW-BASIC | 10 DIM S1$ 'implicitly defined empty string
20 S2$ = "" 'explicitly defined empty string
30 S3$ = "Foo bar baz"
40 S$=S1$ : GOSUB 200
50 S$=S2$ : GOSUB 200
60 S$=S3$ : GOSUB 200
70 END
200 IF LEN(S$)=0 THEN PRINT "Empty string" ELSE PRINT "Non-empty string"
210 RETURN |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Euphoria | Euphoria | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #F.23 | F# | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Factor | Factor | |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #Mathematica_.2F_Wolfram_Language | Mathematica / Wolfram Language | shE[s_String] := -Plus @@ ((# Log[2., #]) & /@ ((Length /@ Gather[#])/
Length[#]) &[Characters[s]]) |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #MATLAB_.2F_Octave | MATLAB / Octave | function E = entropy(d)
if ischar(d), d=abs(d); end;
[Y,I,J] = unique(d);
H = sparse(J,1,1);
p = full(H(H>0))/length(d);
E = -sum(p.*log2(p));
end; |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #Go | Go | package main
import "fmt"
func halve(i int) int { return i/2 }
func double(i int) int { return i*2 }
func isEven(i int) bool { return i%2 == 0 }
func ethMulti(i, j int) (r int) {
for ; i > 0; i, j = halve(i), double(j) {
if !isEven(i) {
r += j
}
}
return
}
func main()... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #VBScript | VBScript | arr = Array(-7,1,5,2,-4,3,0)
WScript.StdOut.Write equilibrium(arr,UBound(arr))
WScript.StdOut.WriteLine
Function equilibrium(arr,n)
sum = 0
leftsum = 0
'find the sum of the whole array
For i = 0 To UBound(arr)
sum = sum + arr(i)
Next
For i = 0 To UBound(arr)
sum = sum - arr(i)
If leftsum = sum Then
equ... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Wren | Wren | import "/fmt" for Fmt
var equilibrium = Fn.new { |a|
var len = a.count
var equi = []
if (len == 0) return equi // sequence has no indices at all
var rsum = a.reduce { |acc, x| acc + x }
var lsum = 0
for (i in 0...len) {
rsum = rsum - a[i]
if (rsum == lsum) equi.add(i)
l... |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #PureBasic | PureBasic |
EnableExplicit
; assumes an array of non-decreasing positive integers
Procedure.q BinarySearch(Array a.q(1), Target.q)
Protected l = 0, r = ArraySize(a()), m
Repeat
If l > r : ProcedureReturn 0 : EndIf; no match found
m = (l + r) / 2
If a(m) < target
l = m + 1
ElseIf a(m) > target
r ... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #PostScript | PostScript | /fact {
dup 0 eq % check for the argument being 0
{
pop 1 % if so, the result is 1
}
{
dup
1 sub
fact % call recursively with n - 1
mul % multiply the result with n
} ifelse
} def |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Jsish | Jsish | #!/usr/bin/env jsish
/* Even or Odd, in Jsish */
function isEven(n:number):boolean { return (n & 1) === 0; }
provide('isEven', 1);
if (Interp.conf('unitTest')) {
; isEven(0);
; isEven(1);
; isEven(2);
; isEven(-13);
}
/*
=!EXPECTSTART!=
isEven(0) ==> true
isEven(1) ==> false
isEven(2) ==> true
isEven(... |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Stata | Stata | . display comb(5,3)
10 |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Swift | Swift | func factorial<T: BinaryInteger>(_ n: T) -> T {
guard n != 0 else {
return 1
}
return stride(from: n, to: 0, by: -1).reduce(1, *)
}
func binomial<T: BinaryInteger>(_ x: (n: T, k: T)) -> T {
let nFac = factorial(x.n)
let kFac = factorial(x.k)
return nFac / (factorial(x.n - x.k) * kFac)
}
print("b... |
http://rosettacode.org/wiki/Emirp_primes | Emirp primes | An emirp (prime spelled backwards) are primes that when reversed (in their decimal representation) are a different prime.
(This rules out palindromic primes.)
Task
show the first twenty emirps
show all emirps between 7,700 and 8,000
show the 10,000th emirp
In each list, the numbe... | #Pascal | Pascal | program Emirp;
//palindrome prime 13 <-> 31
{$IFDEF FPC}
{$MODE DELPHI}
{$OPTIMIZATION ON}
{$OPTIMIZATION REGVAR}
{$OPTIMIZATION PEEPHOLE}
{$OPTIMIZATION CSE}
{$OPTIMIZATION ASMCSE}
{$Smartlink ON}
{$CODEALIGN proc=32}
{$ELSE}
{$APPLICATION CONSOLE}
{$ENDIF}
uses
primtrial,sysutils; //IntToStr
const... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #Harbour | Harbour | // in Harbour we have several functions to check emptiness of a string, f.e. hb_IsNull(), Len(), Empty() et.c.,
// we can also use comparison expressions like [cString == ""] and [cString != ""], yet the most convenient
// of them is `Empty()` (but that depends on personal coding style).
cString := ""
? Empty( cStrin... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #Haskell | Haskell | import Control.Monad
-- In Haskell strings are just lists (of characters), so we can use the function
-- 'null', which applies to all lists. We don't want to use the length, since
-- Haskell allows infinite lists.
main = do
let s = ""
when (null s) (putStrLn "Empty.")
when (not $ null s) (putStrLn "Not empty... |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Falcon | Falcon | > |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #FALSE | FALSE | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Fantom | Fantom | class Main
{
public static Void main () {}
} |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #MiniScript | MiniScript | entropy = function(s)
count = {}
for c in s
if count.hasIndex(c) then count[c] = count[c]+1 else count[c] = 1
end for
sum = 0
for x in count.values
countOverN = x / s.len
sum = sum + countOverN * log(countOverN, 2)
end for
return -sum
end function
print entropy("122... |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #Modula-2 | Modula-2 | MODULE Entropy;
FROM InOut IMPORT WriteString, WriteLn;
FROM RealInOut IMPORT WriteReal;
FROM Strings IMPORT Length;
FROM MathLib IMPORT ln;
PROCEDURE entropy(s: ARRAY OF CHAR): REAL;
VAR freq: ARRAY [0..255] OF CARDINAL;
i, length: CARDINAL;
h, f: REAL;
BEGIN
(* the entropy of the empt... |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #Haskell | Haskell | import Prelude hiding (odd)
import Control.Monad (join)
halve :: Int -> Int
halve = (`div` 2)
double :: Int -> Int
double = join (+)
odd :: Int -> Bool
odd = (== 1) . (`mod` 2)
ethiopicmult :: Int -> Int -> Int
ethiopicmult a b =
sum $
map snd $
filter (odd . fst) $
zip (takeWhile (>= 1) $ iterate halve... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #XPL0 | XPL0 | code Ran=1, ChOut=8, IntOut=11;
def Size = 1_000_000;
int I, S, A(Size), Hi(Size), Lo(Size);
[for I:= 0 to Size-1 do A(I):= Ran(100) - 50;
S:= 0;
for I:= 0 to Size-1 do [S:= S+A(I); Lo(I):= S];
S:= 0;
for I:= Size-1 downto 0 do [S:= S+A(I); Hi(I):= S];
for I:= 0 to Size-1 do
if Lo(I) = Hi(I) then [IntOut(0, I); ... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #Yorick | Yorick | func equilibrium_indices(A) {
return where(A(psum) == A(::-1)(psum)(::-1));
} |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #Python | Python | def eulers_sum_of_powers():
max_n = 250
pow_5 = [n**5 for n in range(max_n)]
pow5_to_n = {n**5: n for n in range(max_n)}
for x0 in range(1, max_n):
for x1 in range(1, x0):
for x2 in range(1, x1):
for x3 in range(1, x2):
pow_5_sum = sum(pow_5[i] for... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #PowerBASIC | PowerBASIC | function fact1#(n%)
local i%,r#
r#=1
for i%=1 to n%
r#=r#*i%
next
fact1#=r#
end function
function fact2#(n%)
if n%<=2 then fact2#=n% else fact2#=fact2#(n%-1)*n%
end function
for i%=1 to 20
print i%,fact1#(i%),fact2#(i%)
next |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Julia | Julia | iseven(i), isodd(i) |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #K | K |
oddp: {:[x!2;1;0]} /Returns 1 if arg. is odd
evenp: {~oddp[x]} /Returns 1 if arg. is even
Examples:
oddp 32
0
evenp 32
1
|
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Tcl | Tcl | package require Tcl 8.5
proc binom {n k} {
# Compute the top half of the division; this is n!/(n-k)!
set pTop 1
for {set i $n} {$i > $n - $k} {incr i -1} {
set pTop [expr {$pTop * $i}]
}
# Compute the bottom half of the division; this is k!
set pBottom 1
for {set i $k} {$i > 1} {incr i -1... |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #TI-83_BASIC | TI-83 BASIC | 10 nCr 4 |
http://rosettacode.org/wiki/Emirp_primes | Emirp primes | An emirp (prime spelled backwards) are primes that when reversed (in their decimal representation) are a different prime.
(This rules out palindromic primes.)
Task
show the first twenty emirps
show all emirps between 7,700 and 8,000
show the 10,000th emirp
In each list, the numbe... | #Perl | Perl | use feature 'say';
use ntheory qw(forprimes is_prime);
# Return the first $count emirps using expanding segments.
# Can efficiently generate millions of emirps.
sub emirp_list {
my $count = shift;
my($i, $inc, @n) = (13, 100+10*$count);
while (@n < $count) {
forprimes {
push @n, $_ if is_prime(reverse... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #HolyC | HolyC | /* assign an empty string */
U8 *str = StrNew("");
/* or */
U8 *str = "";
/* to test if string is empty */
if (StrLen(str) == 0) { ... }
/* or compare to a known empty string. "== 0" means strings are equal */
if (StrCmp(str, "") == 0) { ... }
/* to test if string is not empty */
if (StrLen(str)) { ... } |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #i | i | software {
s = ""
// Can either compare the string to an empty string or
// test if the length is zero.
if s = "" or #s = 0
print("Empty string!")
end
if s - "" or #s - 0
print("Not an empty string!")
end
}
|
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #FBSL | FBSL | ; |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Fermat | Fermat | ; |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Fish | Fish | |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #NetRexx | NetRexx | /* NetRexx */
options replace format comments java crossref savelog symbols
runSample(Arg)
return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/* REXX ***************************************************************
* 28.02.2013 Walter Pachl
*************************************... |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #HicEst | HicEst | WRITE(Messagebox) ethiopian( 17, 34 )
END ! of "main"
FUNCTION ethiopian(x, y)
ethiopian = 0
left = x
right = y
DO i = x, 1, -1
IF( isEven(left) == 0 ) ethiopian = ethiopian + right
IF( left == 1 ) RETURN
left = halve(left)
right = double(right)
ENDDO
END
FUNCTION hal... |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #zkl | zkl | fcn equilibrium(lst){ // two pass
reg acc=List(), left=0,right=lst.sum(0),i=0;
foreach x in (lst){
right-=x;
if(left==right) acc.write(i);
i+=1; left+=x;
}
acc
} |
http://rosettacode.org/wiki/Equilibrium_index | Equilibrium index | An equilibrium index of a sequence is an index into the sequence such that the sum of elements at lower indices is equal to the sum of elements at higher indices.
For example, in a sequence
A
{\displaystyle A}
:
A
0
=
−
7
{\displaystyle A_{0}=-7}
A
1
=
1
{\displaystyle A_{1}=1}
... | #ZX_Spectrum_Basic | ZX Spectrum Basic | 10 DATA 7,-7,1,5,2,-4,3,0
20 READ n
30 DIM a(n): LET sum=0: LET leftsum=0: LET s$=""
40 FOR i=1 TO n: READ a(i): LET sum=sum+a(i): NEXT i
50 FOR i=1 TO n
60 LET sum=sum-a(i)
70 IF leftsum=sum THEN LET s$=s$+STR$ i+" "
80 LET leftsum=leftsum+a(i)
90 NEXT i
100 PRINT "Numbers: ";
110 FOR i=1 TO n: PRINT a(i);" ";: NEXT i... |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #QL_SuperBASIC | QL SuperBASIC |
1 CLS
2 DIM i%(255,6) : DIM a%(6) : DIM c%(6)
3 DIM v%(255,6) : DIM b%(6) : DIM d%(29)
4 RESTORE 137
6 FOR m=0 TO 6
7 READ t%
8 FOR j=1 TO 255
11 LET i%(j,m)=j MOD t%
12 LET v%(j,m)=(i%(j,m) * i%(j,m))MOD t%
14 LET v%(j,m)=(v%(j,m) * v%(j,m))MOD t%
15 LET v%(j,m)=(v%(j,m) * i%(j,m))MOD t%
17 END FOR j : ... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #PowerShell | PowerShell | function Get-Factorial ($x) {
if ($x -eq 0) {
return 1
}
return $x * (Get-Factorial ($x - 1))
} |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Klingphix | Klingphix | ( -5 5 ) [
dup print " " print 2 mod ( ["Odd"] ["Even"] ) if print nl
] for
" " input |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Kotlin | Kotlin | // version 1.0.5-2
fun main(args: Array<String>) {
while (true) {
print("Enter an integer or 0 to finish : ")
val n = readLine()!!.toInt()
when {
n == 0 -> return
n % 2 == 0 -> println("Your number is even")
else -> println("Your number is odd"... |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #TI-89_BASIC | TI-89 BASIC | nCr(n,k) |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #TXR | TXR | $ txr -p '(n-choose-k 20 15)'
15504 |
http://rosettacode.org/wiki/Emirp_primes | Emirp primes | An emirp (prime spelled backwards) are primes that when reversed (in their decimal representation) are a different prime.
(This rules out palindromic primes.)
Task
show the first twenty emirps
show all emirps between 7,700 and 8,000
show the 10,000th emirp
In each list, the numbe... | #Phix | Phix | with javascript_semantics
sequence emirps = {}
function rev(integer n)
integer res = 0
while n do
res = res*10+remainder(n,10)
n = floor(n/10)
end while
return res
end function
function emirp(integer n)
if is_prime(n) then
integer r = rev(n)
if r!=n and is_prime(r... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #Icon_and_Unicon | Icon and Unicon | s := "" # null string
s := string('A'--'A') # ... converted from cset difference
s := char(0)[0:0] # ... by slicing
s1 == "" # lexical comparison, could convert s1 to string
s1 === "" # comparison won't force conversion
*s1 = 0 # zero length, howev... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #J | J | variable=: ''
0=#variable
1
0<#variable
0 |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Forth | Forth | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Fortran | Fortran | end |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #FreeBASIC | FreeBASIC | |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #Nim | Nim | import tables, math
proc entropy(s: string): float =
var t = initCountTable[char]()
for c in s: t.inc(c)
for x in t.values: result -= x/s.len * log2(x/s.len)
echo entropy("1223334444") |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #Objeck | Objeck | use Collection;
class Entropy {
function : native : GetShannonEntropy(result : String) ~ Float {
frequencies := IntMap->New();
each(i : result) {
c := result->Get(i);
if(frequencies->Has(c)) {
count := frequencies->Find(c)->As(IntHolder);
count->Set(count->Get() + 1);
}... |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #Icon_and_Unicon | Icon and Unicon | procedure main(arglist)
while ethiopian(integer(get(arglist)),integer(get(arglist))) # multiply successive pairs of command line arguments
end
procedure ethiopian(i,j) # recursive Ethiopian multiplication
return ( if not even(i) then j # this exploi... |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #Racket | Racket | #lang racket
(define MAX 250)
(define pow5 (make-vector MAX))
(for ([i (in-range 1 MAX)])
(vector-set! pow5 i (expt i 5)))
(define pow5s (list->set (vector->list pow5)))
(let/ec break
(for* ([x0 (in-range 1 MAX)]
[x1 (in-range 1 x0)]
[x2 (in-range 1 x1)]
[x3 (in-range 1 x2)])
(defin... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #Processing | Processing |
int fact(int n){
if(n <= 1){
return 1;
} else{
return n*fact(n-1);
}
}
|
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #Lambdatalk | Lambdatalk |
{def is_odd {lambda {:i} {= {% :i 2} 1}}}
-> is_odd
{def is_even {lambda {:i} {= {% :i 2} 0}}}
-> is_even
{is_odd 2}
-> false
{is_even 2}
-> true
|
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #UNIX_Shell | UNIX Shell | #!/bin/sh
n=5;
k=3;
calculate_factorial(){
partial_factorial=1;
for (( i=1; i<="$1"; i++ ))
do
factorial=$(expr $i \* $partial_factorial)
partial_factorial=$factorial
do... |
http://rosettacode.org/wiki/Evaluate_binomial_coefficients | Evaluate binomial coefficients | This programming task, is to calculate ANY binomial coefficient.
However, it has to be able to output
(
5
3
)
{\displaystyle {\binom {5}{3}}}
, which is 10.
This formula is recommended:
(
n
k
)
=
n
!
(
n
−
k
)
!
k
!
=
n
(
n
−
1
)
(
n
−
2
)
…
(
n
−
k
+
1
)
k
(
k
−
1... | #Ursala | Ursala | #import nat
choose = ~&ar^?\1! quotient^\~&ar product^/~&al ^|R/~& predecessor~~ |
http://rosettacode.org/wiki/Emirp_primes | Emirp primes | An emirp (prime spelled backwards) are primes that when reversed (in their decimal representation) are a different prime.
(This rules out palindromic primes.)
Task
show the first twenty emirps
show all emirps between 7,700 and 8,000
show the 10,000th emirp
In each list, the numbe... | #PHP | PHP | <?php
function is_prime($n) {
if ($n <= 3) {
return $n > 1;
} elseif (($n % 2 == 0) or ($n % 3 == 0)) {
return false;
}
$i = 5;
while ($i * $i <= $n) {
if ($n % $i == 0) {
return false;
}
$i += 2;
if ($n % $i == 0) {
return fa... |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #Java | Java | String s = "";
if(s != null && s.isEmpty()){//optionally, instead of "s.isEmpty()": "s.length() == 0" or "s.equals("")"
System.out.println("s is empty");
}else{
System.out.println("s is not empty");
} |
http://rosettacode.org/wiki/Empty_string | Empty string | Languages may have features for dealing specifically with empty strings
(those containing no characters).
Task
Demonstrate how to assign an empty string to a variable.
Demonstrate how to check that a string is empty.
Demonstrate how to check that a string is not empty.
Other tasks related to string oper... | #JavaScript | JavaScript | var s = "";
var s = new String(); |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #friendly_interactive_shell | friendly interactive shell | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #Frink | Frink | |
http://rosettacode.org/wiki/Empty_program | Empty program | Task
Create the simplest possible program that is still considered "correct."
| #FunL | FunL | |
http://rosettacode.org/wiki/Entropy | Entropy | Task
Calculate the Shannon entropy H of a given input string.
Given the discrete random variable
X
{\displaystyle X}
that is a string of
N
{\displaystyle N}
"symbols" (total characters) consisting of
n
{\displaystyle n}
different characters (n=2 for binary), the Shannon entropy of X in bit... | #OCaml | OCaml | (* generic OCaml, using a mutable Hashtbl *)
(* pre-bake & return an inner-loop function to bin & assemble a character frequency map *)
let get_fproc (m: (char, int) Hashtbl.t) :(char -> unit) =
(fun (c:char) -> try
Hashtbl.replace m c ( (Hashtbl.find m c) + 1)
with Not_fou... |
http://rosettacode.org/wiki/Ethiopian_multiplication | Ethiopian multiplication | Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.
Method:
Take two numbers to be multiplied and write them down at the top of two columns.
In the left-hand column repeatedly halve the last number, discarding any remainders, and write the result below the last ... | #J | J | double =: 2&*
halve =: %&2 NB. or the primitive -:
odd =: 2&|
ethiop =: +/@(odd@] # (double~ <@#)) (1>.<.@halve)^:a: |
http://rosettacode.org/wiki/Euler%27s_sum_of_powers_conjecture | Euler's sum of powers conjecture | There is a conjecture in mathematics that held for over two hundred years before it was disproved by the finding of a counterexample in 1966 by Lander and Parkin.
Euler's (disproved) sum of powers conjecture
At least k positive kth powers are required to sum to a kth power,
except for the trivial case... | #Raku | Raku | constant MAX = 250;
my %po5{Int};
my %sum2{Int};
(1..MAX).map: -> $i {
%po5{$i**5} = $i;
for 1..MAX -> $j {
%sum2{$i**5 + $j**5} = ($i, $j);
}
}
my @sk = %sum2.keys.sort;
%po5.keys.sort.race.map: -> $p {
for @sk -> $s {
next if $p <= $s;
if %sum2{$p - $s} {
say ... |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterat... | #Prolog | Prolog | fact(X, 1) :- X<2.
fact(X, F) :- Y is X-1, fact(Y,Z), F is Z*X. |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #L.2B.2B | L++ | (defn bool isEven (int x) (return (% x 2))) |
http://rosettacode.org/wiki/Even_or_odd | Even or odd | Task
Test whether an integer is even or odd.
There is more than one way to solve this task:
Use the even and odd predicates, if the language provides them.
Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
Divide i by 2. The remainder equals... | #LabVIEW | LabVIEW | : even? 2 % not ;
: odd? 2 % ;
1 even? . # 0
1 odd? . # 1 |
Subsets and Splits
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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.
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