The correct, optimal and working solution for programming question flatland-space-stations 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 compar(const void * a, const void * b) { return *((int *)a) > *((int *)b); } int main(int argc, char *argv[]) { int n, k; scanf("%d%d", &n, &k); int * arr = (int *) calloc(k, sizeof(int)); for(int i = 0 ; i < n ; i++) { scanf("%d", &arr[i]); } if(k == n) { printf("0\n"); } else { qsort(arr, k, sizeof(int), compar); int ans = INT_MIN; for(int i = 0 ; i < (k - 1) ; i++) { int res = 0; if(arr[i+1] - arr[i] == 1) { res = 0; } else { res = (arr[i+1] - arr[i]) / 2; } ans = MAX(ans, res); } ans = MAX(ans, arr[0]); ans = MAX(ans, n - 1 - arr[k-1]); printf("%d\n", ans); } free(arr); return 0; }