题目描述

https://www.acwing.com/problem/content/791/

C++ 代码

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
    int n,m;
    int q[100010];
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++) scanf("%d",&q[i]);
    while(m--)
    {
        int x;
        scanf("%d",&x);
        int l=1,r=n;
        while(l<r)
        {
            int mid=(l+r)>>1;
            if(q[mid]>=x) r=mid;
            else l=mid+1;
        }
        if(q[l]!=x) cout<<"-1 -1"<<endl;
        else
        {
            cout<<l-1<<' ';
            int l=1,r=n;
            while(l<r)
            {
                int mid=(l+r+1)>>1;
                if(q[mid]<=x) l=mid;
                else r=mid-1;
            }
            cout<<l-1<<endl;
        }
    }
    return 0;
}