CF814B An express train to reveries

思路：

模拟，枚举。

实现：

#include <iostream>
using namespace std;

const int N = 1005;

int a[N], b[N], cnt[N], n, x, y;

int main()
{
    cin >> n;
    for (int i = 0; i < n; i++) cin >> a[i], cnt[a[i]]++;
    for (int i = 0; i < n; i++) cin >> b[i];
    for (int i = 1; i <= n; i++)
    {
        if (cnt[i] == 2) x = i;
        else if (cnt[i] == 0) y = i;
    }
    for (int i = 0; i < n; i++)
    {
        if (a[i] == x)
        {
            a[i] = y;
            int bad = 0;
            for (int j = 0; j < n; j++)
                if (b[j] != a[j]) bad++;
            if (bad == 1)
            {
                for (int j = 0; j < n; j++) cout << a[j] << " ";
                return 0;
            }
            a[i] = x;
        }
    }
    return 0;
}