0pts，大佬救救孩子吧（二分）

#include<bits/stdc++.h>
#define int long long
const int N = 1e5 + 5;
int n,m;
int a[N],b[N];
bool tot[N];
using namespace std;
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(nullptr);

    int n,m;
    cin >> n >> m;
    for(int i = 1;i <= n;++i){
        cin >> a[i];
    }
    for(int i = 1;i <= m;++i){
        cin >> b[i];
    } 

    sort(b + 1,b + m + 1);
    for(int i = 1;i <= n;++i){
        int ans = -1;
        int l = 1, r = m;
        while(l <= r) {
            int mid = l + (r - l) / 2;
            if(b[mid] < a[i]){
                l = mid + 1;
            } else if(b[mid] > a[i]) {
                r = mid - 1;
            } else if(b[mid] == a[i]) {
                ans = mid;
                break;
            }
        }
        if(ans != -1) cout << a[i] << " ";
    }
    return 0;
}