Using C++, write a program that satisfies this prompt about permutations: Using

Question

Using C++, write a program that satisfies this prompt about permutations:

Using C++, write a program that satisfies this prompt about permutations: A permutation of a string is the set of all possible ways to combine its characters. E.g.. the permutation of ^''abc^'' is {^''abc^'', ^''acb^'', ^''bac^'', ^''bca^'', ^''cab^'', ^''cba^'' . The size of this set is the factorial of the initial string size. Given a string S (with up to 20 characters, all lowercase letters) and a integer N (0 less than equal to N

Explanation / Answer

#include <iostream>
#include <algorithm>
#include <fstream>
using namespace std;

void permute(string a, int l, int r, int need, int *count){
   if(l == r){
       if(*count == need){
           cout << a << " ";
       }
       (*count)++;
   }
   else{
       for(int i = l; i <= r; i++){
           char temp = a[l];
           a[l] = a[i];
           a[i] = temp;
           permute(a, l + 1, r, need, count);
           temp = a[l];
           a[l] = a[i];
           a[i] = temp;
       }
   }
}
int main(){
   ifstream inFile("input.txt");
   int n;
   inFile >> n;
   while(n--){
       int count = 0;
       string str;
       int need;
       inFile >> str;
       inFile >> need;
       sort(str.begin(), str.end());
       permute(str, 0, str.size() - 1, need, &count);
   }
}

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