二分模板

789 题 数的范围

#include<iostream>

using namespace std;

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

int main()
{
    scanf("%d%d",&n,&m);
    for(int i = 0; i < n ; i++) cin >> q[i] ;
    while(m --)
    {
        int x;
        scanf("%d",&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 <<" ";
            int 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 << l <<endl;
        }

    }
    return 0;
}