python/TangDou/AcWing/BinarySearch/789.cpp

#include <bits/stdc++.h>
using namespace std;

const int N = 100010;
int n;
int q[N];
// 左闭右开 [ )
int lower_bound(int l, int r, int x) {
    while (l < r) {
        int mid = (l + r) >> 1;
        if (q[mid] >= x)
            r = mid;
        else
            l = mid + 1;
    }
    return l;
}
int upper_bound(int l, int r, int x) {
    while (l < r) {
        int mid = (l + r) >> 1;
        if (q[mid] > x)
            r = mid;
        else
            l = mid + 1;
    }
    return l;
}
int main() {
    int T;
    cin >> n >> T;
    for (int i = 0; i < n; i++) cin >> q[i];
    while (T--) {
        int x;
        cin >> x;
        int i = lower_bound(0, n, x); //[0,n)
        if (q[i] != x) {
            puts("-1 -1");
            continue;
        }
        printf("%d ", i);
        i = upper_bound(0, n, x);
        printf("%d\n", i - 1);
    }
    return 0;
}