#include <bits/stdc++.h>
#define ll long long
using namespace std;
int x,y;
int A[70],B[70];
int main(){
cin >> x;
for(int i = 1,v;i <= x;i++) cin >> v,A[v]++;
cin >> y;
for(int i = 1,v;i <= y;i++) cin >> v,B[v]++;
cout << x <<"\n";
for(int i = 0;i <= 70;i++) if(A[i] > 0 && B[i] > 0) cout << i <<" ";
cout <<"\n";
for(int i = 0;i <= 70;i++) if(A[i] > 0 || B[i] > 0) cout << i <<" ";
cout <<"\n";
return 0;
}

上面的代码，5个点全部WA。

下面的代码，AC了。我真的是晕了，这两段代码完全没有区别啊。

#include <bits/stdc++.h>
#define ll long long
using namespace std;
int x,y;
int A[70],B[70];
int main(){
cin >> x;
for(int i = 1,v;i <= x;i++) cin >> v,A[v] = 1;
cin >> y;
for(int i = 1,v;i <= y;i++) cin >> v,B[v] = 1;
cout << x <<"\n";
for(int i = 0;i <= 63;i++) if(A[i] == 1 && B[i] == 1) cout << i <<" ";
cout <<"\n";
for(int i = 0;i <= 63;i++) if(A[i] == 1 || B[i] == 1) cout << i <<" ";
cout <<"\n";
return 0;
}