CF1883E - Look Back

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e5 + 10;
int t, n, ans, Last;
int Arr[N];
int count(int x) { return log2(x) + 1; }
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> t;
    while (t--) {
        ans = Last = 0;
        cin >> n;
        for (int i = 1; i <= n; i++) cin >> Arr[i];
        for (int i = 2; i <= n; i++) {
            if (Arr[i] < Arr[i - 1]) { // 降序
                Last += ceil(log2(Arr[i - 1] * 1.0 / Arr[i]));
                Last = max(0LL, Last);
                ans += Last;
            } else {
                Last -= (int)(log2(Arr[i] * 1.0 / Arr[i - 1]));
                Last = max(0LL, Last);
                ans += Last;
            }
        }
        cout << ans << '\n';
    }
}