[GE][First Method]Find smallest permutation of given number

Smallest number by rearranging digits of a given number

Find the Smallest number (Not leading Zeros) which can be obtained by rearranging the digits of given number.

Examples:

Input: n = 846903
Output: 304689

Input: n = 55010
Output: 10055

Steps to find the smallest number.

1. Count the frequency of each digit in the number.
2. Place the smallest digit (except 0) at the left most of required number.
   and decrement the frequency of that digit by 1.
3. Place all remaining digits in ascending order from left to right.

This solution is based on counting sort.

// C++ program for finding smallest number // from digits of given number #include<iostream> using namespace std;    // function to find the smallest number int smallest(int num) {     // initialize frequency of each digit to Zero     int freq[10] = {0};        // count frequency of each digit in the number     while (num)     {         int d = num % 10; // extract last digit         freq[d]++; // increment counting         num = num / 10; //remove last digit     }        // Set the LEFTMOST digit to minimum expect 0     int result = 0;     for (int i = 1 ; i <= 9 ; i++)     {         if (freq[i])         {             result = i;             freq[i]--;             break;         }     }        // arrange all remaining digits     // in ascending order     for (int i = 0 ; i <= 9 ; i++)         while (freq[i]--)             result = result * 10 + i;        return result; }    // Driver Program int main() {     int num = 570107;     cout << smallest(num);     return 0; }

Output:

100577

// Java program for finding smallest number // from digits of given number public class GFG {        // function to find the smallest number     static int smallest(int num)     {         // initialize frequency of each digit to Zero         int[] freq = new int[10];                 // count frequency of each digit in the number         while (num > 0)         {             int d = num % 10; // extract last digit             freq[d]++; // increment counting             num = num / 10; //remove last digit         }                 // Set the LEFTMOST digit to minimum expect 0         int result = 0;         for (int i = 1 ; i <= 9 ; i++)         {             if (freq[i] != 0)             {                 result = i;                 freq[i]--;                 break;             }         }                 // arrange all remaining digits         // in ascending order         for (int i = 0 ; i <= 9 ; i++)             while (freq[i]-- != 0)                 result = result * 10 + i;                 return result;     }             // Driver Program     public static void main(String args[])     {         int num = 570107;         System.out.println(smallest(num));     } } // This code is contributed by Sumit Ghosh

Output:

100577