解法:
#include<iostream>
#include<vector>
using namespace std;
void solve() {int n;cin >> n;vector<int> vec(n);for (int& x : vec) cin >> x;int x;cin >> x;int l = 0, r = n-1, cnt = 0;while (l <= r) {cnt++;int mid = l + (r - l) / 2;if (vec[mid] > x) r = mid - 1;else if (vec[mid] < x)l = mid + 1;else {cout << mid << endl;cout << cnt;return;}}cout << -1 << endl;cout << cnt;
}
int main() {solve();return 0;
}