The correct, optimal and working solution for programming question cavity-map 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; } char arr[110][110]; int main(int argc, char *argv[]) { int n; cin >> n; for(int i = 0 ; i < n ; i++) { scanf("%s", arr[i]); } for(int i = 1; i < n-1; i++) { for(int j = 1; j < n -1 ; j++) { int d = arr[i][j] - '0'; if(arr[i][j] != 'X' && ((arr[i-1][j] - '0') < d && (arr[i+1][j] - '0') < d && (arr[i][j - 1] - '0') < d && (arr[i][j+1] - '0') < d)) { arr[i][j] = 'X'; } } } for(int i = 0 ; i < n ; i++) { printf("%s\n", arr[i]); } return 0; }