题解

#include <bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int a[N],x,n,q;
int findX(int a[],int n,int x){
	int left=1,right=n,pos=-1;
	while(left<=right){
		int mid=(left+right)/2;
		if(a[mid]<x) left=mid+1;
		else if(a[mid]>x) right=mid-1;
		else{
			pos=mid;
			break;
		}
	}
	return pos;
}
int main(){
	cin>>n>>q;
	for(int i=1;i<=n;i++) cin>>a[i];
	for(int j=1;j<=q;j++){
		cin>>x;
		cout<<findX(a,n,x)<<endl;
	}
	return 0;
}