The correct, optimal and working solution for programming question lazy-mayor-and-lasers 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; int readline(char *str) { int i = 0; char ch; while((ch = getchar()) != '\n') { str[i++] = ch; } str[i] = '\0'; return i; } ll int arr[100010]; int cuts[100010]; ll int min(ll int a, ll int b) { return (a < b) ? a : b; } int compar(const void * a, const void * b) { return (*(int *)a) > (*(int *)b); } ll int process(int n, int m) { ll int sum = 0; qsort(cuts, m, sizeof(int), compar); for(int i = 0; i < m; i++) { int start = 0, end = 0; if(i == 0) { start = 0; end = cuts[i] - 1; } else { start = cuts[i-1] - 1; end = cuts[i] - 1; } for(int j = start; j < end; j++) { arr[j] = min(end - j, arr[j]); } } for(int i = 0; i < n; i++) { sum += arr[i]; } return sum; } int main(int argc, char *argv[]) { int n; scanf("%d", &n); for(int i = 0 ; i < n; i++) { scanf("%lld", &arr[i]); } int m; scanf("%d", &m); for( int i = 0 ; i < m; i++) { scanf("%d", &cuts[i]); } printf("%lld\n", process(n, m)); return 0; }