二分模板代码

//二分模板
#include
using namespace std;
using ll = long long;
const int N = 2e5 + 9;
 
int a[N];
 
void slove()
{
	int n, q; cin >> n >> q;
	for (int i = 1; i <= n; ++i)cin >> a[i];
 
	while (q--)
	{
		int x; cin >> x;
		int l = 0, r = n;
		while (l + 1 != r)
		{
			int mid = (l + r) >> 1;
			if (a[mid] < x) l = mid;//l始终比mid小
			else r = mid;//r始终大于等于mid
		}
		if (a[r] == x) cout << r << ' ';
		else cout << -1 << ' ';
	}
}
 
int main()
{
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	int t = 1;
	while (t--) slove();
	return 0;
}