789. 数的范围

Posted 2021-05-20 幽殇默

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

#include<cstdio>
#include<iostream>
using namespace std;
const int N=1e5+10;
int a[N],n,q;
int main(void)
{
	cin>>n>>q;
	for(int i=0;i<n;i++) cin>>a[i];
	while(q--)
	{
		int k; cin>>k;
		int l=0,r=n-1;
		while(l<r)
		{
			int mid=l+r>>1;
			if(a[mid]>=k) r=mid;
			else l=mid+1;
		}
		if(a[l]==k) cout<<l<<" ";
		else cout<<"-1 ";
		
		l=0,r=n-1;
		while(l<r)
		{
			int mid=l+r+1>>1;
			if(a[mid]<=k) l=mid;
			else r=mid-1;
		}
		if(a[l]==k) cout<<l<<" ";
		else cout<<"-1 ";
		cout<<endl;
	}
	return 0;
}