```cpp
#include <iostream>
using namespace std;
int m1[1000010], m2[100010];
int main() {
int a, b;
cin >> a >> b;
for (int i = 1; i <= a; i++)
cin >> m1[i];
for (int i = 0; i < b; i++)
cin >> m2[i];
for (int i = 0; i < b; i++) {
int l = 1, r = a, ans = -1;
while (l <= r) {
int m = (l + r) / 2;
if (m1[m] < m2[i])
l = m + 1;
else {
ans = m;
r = m - 1;
}
}
if (ans != -1 && m1[ans] == m2[i])
cout << ans << " ";
else
cout << "-1 ";
}
return 0;
}
```
by hopefire @ 2024-04-24 18:23:24
@[caozeheng](/user/1313368) 改了一下
by hopefire @ 2024-04-24 18:23:49
没学过binary_search和lower_bound吗？
用上这两个函数试试，一个判断，一个查找
by B2303huangfeidong @ 2024-04-24 18:25:03
```cpp
#include<iostream>
using namespace std;
int a[1000005];
int n,m;
int find(int x){
int l=0,r=n+1;
while(l+1<r){
int mid=(l+r)/2;
if(a[mid]>=x){
r=mid;
}else{
l=mid;
}
}
if(a[r]==x){
return r;
}
return -1;
}
int main(){
cin>>n>>m;
for(int i=1;i<=n;i++){
cin>>a[i];
}
a[0]=-10;
a[n+1]=1.5e9;
for(int i=1;i<=m;i++){
int x;
cin>>x;
cout<<find(x)<<" ";
}
return 0;
}
```
by 20121028LRR @ 2024-04-24 19:15:55
@[B2303huangfeidong](/user/1035415) 读题cout下标
by yanghexie @ 2024-04-28 21:26:53
@[yanghexie](/user/1014678) 好吧我是小丑
by yanghexie @ 2024-04-28 21:27:48