题目
方便自己以后复习

代码：

#include <bits/stdc++.h>

using namespace std;
typedef long long LL;
const int maxn = 1e6+9;
int a[maxn];
int main()
{
    int m,n;
    cin>>n>>m;
    for(int i=1;i<=n;i++) scanf("%d",&a[i]);
    for(int i=1;i<=m;i++)
    {
        LL num;
        scanf("%d",&num);
        int l = 1;
        int r = n;
        int pos = -1;
        while(l<=r)
        {
            int mid = (r+l)>>1;
            if(a[mid]>num) r = mid-1;
            else if(a[mid]<num) l = mid+1;
            else
            {
                pos = mid;
                r = mid-1;
            }
        }
        printf("%d ",pos);
    }
    return 0;
}