二分

#include<bits/stdc++.h>
using namespace std;
int main(){
int n,m,b=0;cin>>n>>m;
int a[103129];
for(int i=1;i<=n;i++){
cin>>a[i];
}for(int i=1;i<=m;i++){
cin>>b;
int c=-1;
int l=1,r=n,mid;
while(l<=r){
mid=(l+r)/2;
if(a[mid]==b){
c=mid;
r=mid-1;
}else if(a[mid]>b){
r=mid-1;
}else if(a[mid]<b){
l=mid+1;
}
}cout<<c<<"\n";
}
return 0;
}