CODE EXAMPLE FOR CPP

permutation and combination program in c++

// C++ program to print all 
// permutations with duplicates allowed 
#include <bits/stdc++.h> 
using namespace std; 
  
  
// Function to print permutations of string 
// This function takes three parameters: 
// 1. String 
// 2. Starting index of the string 
// 3. Ending index of the string. 
void permute(string a, int l, int r) 
{ 
    // Base case 
    if (l == r) 
        cout<<a<<endl; 
    else
    { 
        // Permutations made 
        for (int i = l; i <= r; i++) 
        { 
  
            // Swapping done 
            swap(a[l], a[i]); 
  
            // Recursion called 
            permute(a, l+1, r); 
  
            //backtrack 
            swap(a[l], a[i]); 
        } 
    } 
} 
  
// Driver Code 
int main() 
{ 
    string str = "ABC"; 
    int n = str.size(); 
    permute(str, 0, n-1); 
    return 0; 
}