【整数二分】

数的范围

#include<iostream>
using namespace std;
const int N = 100000 + 11;int n;
int q;
int a[N];int key;int main(){cin>>n>>q;for(int i=0;i<n;i++)cin>>a[i];while(q--){cin>>key;//先去找左（大于等于）再去找右（小于等于）//大于等于就是（找左端点，对应模板的右区间）//小于等于就是（找右端点，对应模板的左区间）int l = 0;int r = n-1;while(l<r){//mid在while循环中定义int mid = (l+r)>>1;if(a[mid]>=key) r = mid;else    l = mid+1;}if(a[l]!=key)cout<<"-1 -1"<<endl;else{cout<<l<<" ";l = 0;r = n-1;while(l<r){int mid = (l+r+1)>>1;if(a[mid]<=key) l = mid;else    r = mid-1;}cout<<l<<endl;}}return 0;
}