二分查找模板2

#include<bits/stdc++.h>
using namespace std;
int lower_bound(int a[],int left,int right,int x)
{
	while(left<=right)
	{
		int mid=(left+right)/2;
		if(a[mid]>=x) right=mid-1;
		else left=mid+1;
	}
	return left;
}
int main()
{
	int n,m,i;
	cin>>n>>m;
	int a[n];
	for(i=0;i<n;i++) cin>>a[i];
	sort(a,a+n);
	
	for(i=0;i<m;i++)
	{
		int x;
		cin>>x;
		if(x<a[0]) cout<<a[0]<<endl;
		else if(x>a[n-1]) cout<<"-1\n";
		else 
		{
			int pos=lower_bound(a,0,n-1,x);
			cout<<a[pos]<<endl;	
		}	
	}	
}