1554B - Cobb - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
#define ll long long int
#define f first
#define s second
int main()
{
	int t = 1;
	cin >> t;
	while (t--) {
		int i, j, k, l, n;
		cin >> n >> k;
		vector<int> a(n);
		for (i = 0; i < n; i++) {
			cin >> a[i];
		}
		ll ans = 1ll * -100000 * 100000;
		for(i = max(n - 200, 0); i < n; i++) {
			for (j = i + 1; j < n; j++) {
				ans = max(ans, 1ll *(i + 1) * (j + 1) - 1ll * k * (a[i] | a[j]));
			}
		}
		cout << ans << endl;
	}
}