整数二分

重点
1. 二分的时候，注意是求>=，还是<=，如果是<=, 则求mid的时候需要加1
2. if中的判断可以改成check，用来做局部性判断，这要求二分的序列需要有局部性质，一部分check=1，另一份check一定=0，

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 100010;
int q[N];


int main() {
    int n, k;
    cin >> n >> k;
    for (int i = 0; i < n; i++) cin >> q[i];
    for (int i = 0; i < k; i++) {
        int a;
        cin >> a;
        int l = 0, r = n - 1;
        while (l < r) {
            int mid = (l + r) >> 1;
            if (q[mid] >= a) r = mid;
            else l = mid + 1;
        }
        int t = l;
        if (q[t] == a) {
            cout << t << " ";
            int l = 0, r = n - 1;
            while (l < r) {
                int mid = (l + r + 1) >> 1;
                if (q[mid] <= a) l = mid;
                else r = mid - 1;
            }
            cout << l << endl;
        } else cout << "-1 -1" << endl;
    }    
    return 0;
}