hdu 5495 LCS (置换群)

Sample Input
2
3
1 2 3
3 2 1
6
1 5 3 2 6 4
3 6 2 4 5 1
 

Sample Output
2
4

C/C++：

#include <map>
#include <queue>
#include <cmath>
#include <vector>
#include <string>
#include <cstdio>
#include <cstring>
#include <climits>
#include <iostream>
#include <algorithm>
#define INF 0x3f3f3f3f
#define LL long long
using namespace std;
const int MAX = 1e5 + 10;

int a[MAX], b[MAX], c[MAX], vis[MAX], n, t, ans;

int main()
{
    scanf("%d", &t);
    while (t --)
    {
        scanf("%d", &n);
        for (int i = 1; i <= n; ++ i)
        {
            scanf("%d", &a[i]);
            vis[i] = 0;
        }
        for (int i = 1; i <= n; ++ i)
            scanf("%d", &b[i]);
        for (int i = 1; i <= n; ++ i)
            c[a[i]] = b[i];

        ans = n;
        for (int i = 1; i <= n; ++ i)
        {
            int temp = i;
            if (vis[temp]) continue;
            if (temp != c[temp])
            {
                ans --;
                while (!vis[temp])
                {
                    vis[temp] = 1;
                    temp = c[temp];
                }
            }
        }
        printf("%d
", ans);
    }
    return 0;
}