The correct, optimal and working solution for programming question diagonal-difference 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; } int mat[200][200]; int main(int argc, char *argv[]) { int n; scanf("%d", &n); for(int i = 0;i < n; i++) { for(int j = 0; j <n; j++) { scanf("%d", &mat[i][j]); } } ll int sum1 = 0, sum2 = 0; for(int i = 0 ; i < n; i++) { sum1 += mat[i][i]; sum2 += mat[i][n-1-i]; } cout << abs(sum1-sum2) << endl; return 0; }