codejam_2016_round1A_C.cpp

 /* 1등 nika 코드 참고함 */  
#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <queue>
#include <sstream>
using namespace std;

#define FOR(i,N) for(int i=1; i<=N; i++)
#define MAXN 1001

int main(){
    freopen("codejam/C/C-large-practice.in", "r", stdin);
    freopen("codejam/C/C-large-practice.out", "w", stdout);

    int T, N;
    cin >> T;

    FOR(t, T){
        int g[MAXN];
        cin >> N;
        FOR(i, N) cin >> g[i];

        int ans = 0;
        bool ck[MAXN];
        FOR(i, N){
            FOR(j, N) ck[j] = false;
            int now = i, depth = 0;
            while(!ck[now]){
                depth++;
                ck[now] = true;
                now = g[now];
            }
            if(now == i) ans = max(ans, depth);
        }

        int dis[MAXN];
        FOR(i, N) dis[i] = 0;
        FOR(i, N) FOR(j, N) if(g[g[j]] != j){
            dis[g[j]] = max(dis[g[j]], dis[j]+1);
        }

        int ans2 = 0;
        FOR(i, N) ck[i] = false;
        FOR(i, N) if(g[g[i]] == i && !ck[i]){
            ck[i] = ck[g[i]] = true;
            ans2 += 2+dis[i]+dis[g[i]];
        }
        printf("Case #%d: %d\n", t, max(ans, ans2));
    }

    return 0;
}