Find the number of good permutations | C ++ implementation of the approach ; Function to return the count of good permutations ; For m = 0 , ans is 1 ; If k is greater than 1 ; If k is greater than 2 ; If k is greater than 3 ; Driver code
#include <bits/stdc++.h> NEW_LINE using namespace std ; int Permutations ( int n , int k ) { int ans = 1 ; if ( k >= 2 ) ans += ( n ) * ( n - 1 ) / 2 ; if ( k >= 3 ) ans += ( n ) * ( n - 1 ) * ( n - 2 ) * 2 / 6 ; if ( k >= 4 ) ans += ( n ) * ( n - 1 ) * ( n - 2 ) * ( n - 3 ) * 9 / 24 ; return ans ; } int main ( ) { int n = 5 , k = 2 ; cout << Permutations ( n , k ) ; return 0 ; }