【題解】Codeforces 1339C. Powered Addition

#include <iostream>
using namespace std;
 
int t, n, a, mx, ans;
 
int main() {
    cin >> t;
    while (t--){
        cin >> n;
        cin >> mx;
        ans = 0;
        for (int i = 1; i < n; i++){
            cin >> a;
            if (a < mx) ans = max(ans, mx-a);
            mx = max(mx, a);
        }
        int k = 0;
        while (ans){
            k++;
            ans /= 2;
        }
        cout << k << "\n";
    }
}