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# Generate all possible permutations of a Number divisible by N

• Last Updated : 12 Jun, 2021

Given a numerical string S, the task is to print all the permutations of the string which are divisible by N.

Examples:

Input: N = 5, S = “125”
Output: 125 215
Explanation:
All possible permutations are S are {125, 152, 215, 251, 521, 512}.
Out of these 6 permutations, only 2 {125, 215} are divisible by N (= 5).

Input: N = 7, S = “4321”
Output: 4312 4123 3241

Approach: The idea is to generate all possible permutations and for each permutation, check if it is divisible by N or not. For each permutation found to be divisible by N, print them.

Below is the implementation of the above approach:

## C++14

 `// C++ Program to implement``// the above approach``#include ``using` `namespace` `std;` `// Function to Swap two``// characters``void` `swap_(``char``& a, ``char``& b)``{``    ``char` `temp;``    ``temp = a;``    ``a = b;``    ``b = temp;``}` `// Function to generate all permutations``// and print the ones that are``// divisible by the N``void` `permute(``char``* str, ``int` `l, ``int` `r, ``int` `n)``{``    ``int` `i;` `    ``if` `(l == r) {` `        ``// Convert string to integer``        ``int` `j = ``atoi``(str);` `        ``// Check for divisibility``        ``// and print it``        ``if` `(j % n == 0)``            ``cout << str << endl;` `        ``return``;``    ``}` `    ``// Print all the permutations``    ``for` `(i = l; i < r; i++) {` `        ``// Swap characters``        ``swap_(str[l], str[i]);` `        ``// Permute remaining``        ``// characters``        ``permute(str, l + 1, r, n);` `        ``// Revoke the swaps``        ``swap_(str[l], str[i]);``    ``}``}` `// Driver Code``int` `main()``{``    ``char` `str = ``"125"``;``    ``int` `n = 5;``    ``int` `len = ``strlen``(str);` `    ``if` `(len > 0)``        ``permute(str, 0, len, n);` `    ``return` `0;``}`

## Java

 `// Java program to implement``// the above approach``class` `GFG{` `// Function to Swap two``// characters``static` `void` `swap_(``char` `[]a, ``int` `l, ``int` `i)``{``    ``char` `temp;``    ``temp = a[l];``    ``a[l] = a[i];``    ``a[i] = temp;``}` `// Function to generate all permutations``// and print the ones that are``// divisible by the N``static` `void` `permute(``char``[] str, ``int` `l,``                         ``int` `r, ``int` `n)``{``    ``int` `i;` `    ``if` `(l == r)``    ``{``        ` `        ``// Convert String to integer``        ``int` `j = Integer.valueOf(String.valueOf(str));` `        ``// Check for divisibility``        ``// and print it``        ``if` `(j % n == ``0``)``            ``System.out.print(String.valueOf(str) + ``"\n"``);` `        ``return``;``    ``}` `    ``// Print all the permutations``    ``for``(i = l; i < r; i++)``    ``{``        ` `        ``// Swap characters``        ``swap_(str, l, i);` `        ``// Permute remaining``        ``// characters``        ``permute(str, l + ``1``, r, n);` `        ``// Revoke the swaps``        ``swap_(str, l, i);``    ``}``}` `// Driver Code``public` `static` `void` `main(String[] args)``{``    ``String str = ``"125"``;``    ``int` `n = ``5``;``    ``int` `len = str.length();` `    ``if` `(len > ``0``)``        ``permute(str.toCharArray(), ``0``, len, n);``}``}` `// This code is contributed by amal kumar choubey`

## Python3

 `# Python3 Program to implement``# the above approach` `# Function to generate all``# permutations and print``# the ones that are``# divisible by the N``def` `permute(st, l, r, n):` `    ``if` `(l ``=``=` `r):` `        ``# Convert string``        ``# to integer``        ``p ``=` `''.join(st)``        ``j ``=` `int``(p)` `        ``# Check for divisibility``        ``# and print it``        ``if` `(j ``%` `n ``=``=` `0``):``            ``print` `(p)` `        ``return` `    ``# Print all the``    ``# permutations``    ``for` `i ``in` `range``(l, r):` `        ``# Swap characters``        ``st[l], st[i] ``=` `st[i], st[l]` `        ``# Permute remaining``        ``# characters``        ``permute(st, l ``+` `1``, r, n)` `        ``# Revoke the swaps``        ``st[l], st[i] ``=` `st[i] ,st[l]` `# Driver Code``if` `__name__ ``=``=` `"__main__"``:` `    ``st ``=` `"125"``    ``n ``=` `5``    ``length ``=` `len``(st)` `    ``if` `(length > ``0``):``      ``p ``=` `list``(st)``      ``permute(p, ``0``, length, n);` `# This code is contributed by rutvik_56`

## C#

 `// C# program to implement``// the above approach``using` `System;` `class` `GFG{`` ` `// Function to Swap two``// characters``static` `void` `swap_(``char` `[]a, ``int` `l,``                            ``int` `i)``{``    ``char` `temp;``    ``temp = a[l];``    ``a[l] = a[i];``    ``a[i] = temp;``}`` ` `// Function to generate all permutations``// and print the ones that are``// divisible by the N``static` `void` `permute(``char``[] str, ``int` `l,``                         ``int` `r, ``int` `n)``{``    ``int` `i;`` ` `    ``if` `(l == r)``    ``{``        ` `        ``// Convert String to integer``        ``int` `j = Int32.Parse(``new` `string``(str));`` ` `        ``// Check for divisibility``        ``// and print it``        ``if` `(j % n == 0)``            ``Console.Write(``new` `string``(str) + ``"\n"``);`` ` `        ``return``;``    ``}`` ` `    ``// Print all the permutations``    ``for``(i = l; i < r; i++)``    ``{``        ` `        ``// Swap characters``        ``swap_(str, l, i);`` ` `        ``// Permute remaining``        ``// characters``        ``permute(str, l + 1, r, n);`` ` `        ``// Revoke the swaps``        ``swap_(str, l, i);``    ``}``}`` ` `// Driver Code``public` `static` `void` `Main(``string``[] args)``{``    ``string` `str = ``"125"``;``    ``int` `n = 5;``    ``int` `len = str.Length;`` ` `    ``if` `(len > 0)``        ``permute(str.ToCharArray(), 0, len, n);``}``}` `// This code is contributed by rutvik_56`

## Javascript

 ``
Output:
```125
215```

Time Complexity: O(N!)
Auxiliary Space: O(N)

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