1010: 折半查找的实现

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;
}