题目

在最后写了个判断，a[r]是查找的最终结果，如果这个

结果不等于目标，说明没找到

#include <iostream>
using namespace std;
#define int long long

const int N = 1e6+10;

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

        int l2 = -1, r2 = n;
        while (l2+1!=r2){
            int mid = l2 + r2 >> 1;
            if(a[mid] <= k)l2 = mid;
            else r2 = mid;
        }

        if (a[r] != k){
            printf("-1 -1\n");
            continue;
        }

        printf("%d %d\n", r, l2);
    }
    return 0;
}