Number of ways such that only K bars are visible from the left | C ++ implementation for the above approach ; Function to calculate the number of permutations of N , where only K bars are visible from the left . ; Only ascending order is possible ; N is placed at the first position The nest N - 1 are arranged in ( N - 1 ) ! ways ; Recursing ; Driver code ; Input ; Function call
#include <bits/stdc++.h> NEW_LINE using namespace std ; int KvisibleFromLeft ( int N , int K ) { if ( N == K ) return 1 ; if ( K == 1 ) { int ans = 1 ; for ( int i = 1 ; i < N ; i ++ ) ans *= i ; return ans ; } return KvisibleFromLeft ( N - 1 , K - 1 ) + ( N - 1 ) * KvisibleFromLeft ( N - 1 , K ) ; } int main ( ) { int N = 5 , K = 2 ; cout << KvisibleFromLeft ( N , K ) << endl ; return 0 ; }