Get the kth smallest number using the digits of the given number

Given a non-negative number n and a value k. Find the kth smallest number that can be formed using the digits of the given number n. It is guaranteed that the kth smallest number can be formed. Note that the number could be very large and may not even fit into long long int.

Examples:

Input : n = 1234, k = 2
Output : 1243

Input : n = 36012679802, k = 4
Output : 10022366897

Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.

The idea is to first sort digits and find the smallest number, then find k-th permutation starting from smallest number. To sort digits, we use an frequency counting technique as number of digits are small.

 // C++ implementation to get the kth smallest // number using the digits of the given number #include using namespace std;    // function to get the smallest digit in 'num' // which is greater than 0 char getSmallDgtGreaterThanZero(string num, int n) {     // 's_dgt' to store the smallest digit     // greater than 0         char s_dgt = '9';            for (int i=0; i

Output:

10022366897

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