The correct, optimal and working solution for programming question strange-advertising on hackerrank

/* * Author: Arpit Bhayani * https://arpitbhayani.me */ #include <cmath> #include <cstdio> #include <cstdlib> #include <climits> #include <deque> #include <iostream> #include <list> #include <limits> #include <map> #include <queue> #include <set> #include <stack> #include <vector> #define ll long long #define MIN(a, b) a < b ? a : b #define MAX(a, b) a > b ? a : b using namespace std; ll int reverse(ll int n) { ll int rn = 0; while(n) { rn = rn * 10 + n % 10; n = n / 10; } return rn; } int main() { int n, sum = 0, people = 0; scanf("%d", &n); // n = 1 sum = 0; people = 5; for(int i = 1 ; i <= n; i++) { sum += people/2; people = (people/2) * 3; } printf("%d\n", sum); return 0; }