Lexicographically n-th permutation of a string

Given a string of length m containing lowercase alphabets only. You have to find the n-th permutation of string lexicographically.

Examples:

Input : str[] = "abc", n = 3
Output : Result = "bac"
Explanation : All possible permutation in
sorted order: abc, acb, bac, bca, cab, cba

Input : str[] = "aba", n = 2
Output : Result = "aba"
Explanation : All possible permutation
in sorted order: aab, aba, baa

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Prerequisite : Permutations of a given string using STL

Idea behind printing n-th permutation is quite simple we should use STL (explained in above link) for finding next permutation and do it till the nth permutation. After n-th iteration, we should break from the loop and then print the string which is our nth permutation.

    long int i = 1;
    do
    {
        // check for nth iteration
        if (i == n)
            break;
       i++; // keep incrementing the iteration
    } while (next_permutation(str.begin(), str.end()));

    // print string after nth iteration
   print str;

// C++ program to print nth permutation with 
// using next_permute() 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to print nth permutation 
// using next_permute() 
void nPermute(string str, long int n) 
{ 
    // Sort the string in lexicographically 
    // ascending order 
    sort(str.begin(), str.end()); 
  
    // Keep iterating until 
    // we reach nth position 
    long int i = 1; 
    do { 
        // check for nth iteration 
        if (i == n) 
            break; 
  
        i++; 
    } while (next_permutation(str.begin(), str.end())); 
  
    // print string after nth iteration 
    cout << str; 
} 
  
// Driver code 
int main() 
{ 
    string str = "GEEKSFORGEEKS"; 
    long int n = 100; 
    nPermute(str, n); 
    return 0; 
} 

Output:

EEEEFGGRKSOSK

Find n-th lexicographically permutation of a string | Set 2

This article is contributed by Shivam Pradhan (anuj_charm). If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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