重铸华农荣光 我辈义不容辞

打卡第三天-dichotomy

#include<iostream>
using namespace std;

const int N=100010;
int n,m;
int q[N];

int main()
{
    cin>>n>>m;
    for(int i=0;i<n;i++) cin>>q[i];

    while(m--){
        int x;
        cin>>x;

        int l=0,r=n-1;
        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<<" ";
            l=0,r=n-1;
            while(l<r){
                int mid=l+r+1>>1;
                if(q[mid]<=x) l=mid;
                else r=mid-1;
            }      
            cout<<r<<" "<<endl;      
        } 
    }

    return 0;
}