Infinite Path CodeForces

题目链接

这个题关键是想明白，K的含义，即，向前跃进几步

代码如下

#include<bits/stdc++.h>
using namespace std;
#define inf 1000000000
#define maxn 200005
vector<int> d[maxn];
int p[maxn], c[maxn];
bool vis[maxn];
int cal(vector<int> loop)
{
    int minn = inf;
    for(int k = 0; k < d[loop.size()].size(); k++){
        int len = d[loop.size()][k];
        for(int i = 0; i < len; i++){
            bool flag = true;
            for(int j = i; j < loop.size(); j += len){
                if(c[loop[i]] != c[loop[j]]){
                    flag = false;
                    break;
                }
            }
            if(flag) minn = min(minn, len);
        }

    }
    return minn;
}
int main()
{
    for(int i = 1; i <= maxn; i++)
        for(int j = i; j < maxn; j+= i)
        d[j].push_back(i);
    int t;
    cin >> t;
    while(t--){
        int n;
        cin >> n;
        for(int i = 1; i <= n; i++) cin >> p[i];
        for(int i = 1; i <= n; i++) cin >> c[i];
        for(int i = 0; i <= n; i++) vis[i] = false;
        int ans = n;
        for(int i = 1; i <= n; i++){
            if(vis[i]) continue;
            int k = i;
            vector<int> loop;
            while(!vis[k]){
                loop.push_back(k);
                vis[k] = true;
                k = p[k];
            }
            ans = min(ans, cal(loop));
        }
        cout << ans << endl;

    }
}