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Find smallest permutation of given number
• Difficulty Level : Easy
• Last Updated : 04 May, 2021

Given a long integer, return the smallest(magnitude) integer permutation of that number.
Examples

```Input : 5468001
Output : 1004568

Input : 5341
Output : 1345```

Question Source : GE digital Interview Experience | Set 6
We have already discussed a solution in below post.
Smallest number by rearranging digits of a given number
In this post, a different approach is discussed.
Approach : As number is long, store the number as string, sort the string, if there is no leading zero, return this string, if there is any leading zero, swap first element of string with first non-zero element of string, and return the string.
Below is the implementation of above approach :

## C++

 `// CPP program to find smallest``// permutation of given number``#include ``using` `namespace` `std;` `// return the smallest number permutation``string findSmallestPermutation(string s)``{``    ``int` `len = s.length();` `    ``// sort the string``    ``sort(s.begin(), s.end());` `    ``// check for leading zero in string``    ``// if there are any leading zeroes,``    ``// swap the first zero with first non-zero number``    ``int` `i = 0;``    ``while` `(s[i] == ``'0'``)``        ``i++;``    ` `    ``swap(s, s[i]);``    ``return` `s;``}` `// driver program``int` `main()``{``    ``// take number input in string``    ``string s = ``"5468001"``;``    ``string res = findSmallestPermutation(s);``    ``cout << res << endl;``    ``return` `0;``}`

## Java

 `// Java program to find smallest``// permutation of given number``import` `java.util.Arrays;` `public` `class` `GFG {``    ` `    ``// return the smallest number permutation``    ``static` `char``[] findSmallestPermutation(String s1)``    ``{``        ``// sort the string``        ``char` `s[] = s1.toCharArray();``        ``Arrays.sort(s);``     ` `        ``// check for leading zero in string``        ``// if there are any leading zeroes,``        ``// swap the first zero with first non-zero``        ``// number``        ``int` `i = ``0``;``        ``while` `(s[i] == ``'0'``)``            ``i++;``         ` `        ``char` `temp = s[``0``];``        ``s[``0``] = s[i];``        ``s[i] = temp;``        ``return` `s;``    ``}``     ` `    ``// driver program``    ``public` `static` `void` `main(String args[])``    ``{``        ``// take number input in string``        ``String s = ``"5468001"``;``        ``char` `res[] = findSmallestPermutation(s);``        ``System.out.println(res);``    ``}``}``// This code is contributed by Sumit Ghosh`

## Python

 `# Python program to find smallest``# permutation of given number` `# Sort function``def` `sort_string(a):``    ``return` `''.join(``sorted``(a))` `# return the smallest number permutation``def` `findSmallestPermutation(s):`` ` `    ``# sort the string``    ``s ``=` `sort_string(s)`` ` `    ``# check for leading zero in string``    ``# if there are any leading zeroes,``    ``# swap the first zero with first non-zero number``    ``i ``=` `0``    ``while` `(s[i] ``=``=` `'0'``):``        ``i ``+``=` `1``    ``a ``=` `list``(s)``    ``temp ``=` `a[``0``]``    ``a[``0``] ``=` `a[i]``    ``a[i] ``=` `temp``    ``s ``=` `"".join(a)``    ``return` `s`` ` `# driver program` `# take number input in string``s ``=` `"5468001"``res ``=` `findSmallestPermutation(s)``print` `res` `# This code is contributed by Sachin Bisht`

## C#

 `// C# program to find smallest``// permutation of given number``using` `System;` `public` `class` `GFG {``    ` `    ``// return the smallest number permutation``    ``static` `char``[] findSmallestPermutation(``string` `s1)``    ``{``        ` `        ``// sort the string``        ``char` `[]s = s1.ToCharArray();;``        ``Array.Sort(s);``    ` `        ``// check for leading zero in string``        ``// if there are any leading zeroes,``        ``// swap the first zero with first non-zero``        ``// number``        ``int` `i = 0;``        ``while` `(s[i] == ``'0'``)``            ``i++;``        ` `        ``char` `temp = s;``        ``s = s[i];``        ``s[i] = temp;``        ``return` `s;``    ``}``    ` `    ``// driver program``    ``public` `static` `void` `Main()``    ``{``        ` `        ``// take number input in string``        ``string` `s = ``"5468001"``;``        ` `        ``char` `[]res = findSmallestPermutation(s);``        ``Console.WriteLine(res);``    ``}``}` `// This code is contributed by vt_m.`

## PHP

 ``

## Javascript

 `// Javascript program to find smallest``// permutation of given number` `// return the smallest``// number permutation``function` `findSmallestPermutation(s)``{``    ``let len = s.length;``    ``s = s.split(``""``);``    ` `    ``// sort the string``    ``s = s.sort();` `    ``// check for leading zero``    ``// in string if there are``    ``// any leading zeroes,``    ``// swap the first zero with``    ``// first non-zero number``    ``let i = 0;``    ``while` `(s[i] == ``'0'``)``        ``i++;``    ` `    ``let tmp = s;``    ``s = s[i];``    ``s[i] = tmp;``    ``s=  s.join(``""``);``    ``return` `s;``}` `// Driver Code` `// take number``// input in string``let s = ``"5468001"``;``let res = findSmallestPermutation(s);``document.write(res);` `// This code is contributed``// by _saurabh_jaiswal`

Output:

`1004568`

Optimization :
Since character set is limited (‘0’ to ‘9’), we can write our own sort method that works in linear time (by counting frequencies of all characters)
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