[C++] 10451 - 순열 사이클

문제 링크 : https://www.acmicpc.net/problem/10451

10451번: 순열 사이클

 

#include<iostream>
#include<algorithm>
#include<cstring> // for memset
#define endl '\n'
 
using namespace std;
int cycle[1005];
bool memo[1005];
int T;
 
int dfs(int start, int end, int n)
{
    for(int i = 1; i <= n; ++i)
    {
        end = cycle[end];
        memo[end] = 1;
        if(start == end)
            return 1;
    }
}
 
int main(void)
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
 
    int n;
    int cnt;
    cin >> T;
    for(int i = 0; i < T; ++i)
    {
        cnt = 0;
        cin >> n;
        for(int j = 1 ; j <= n; ++j)
            cin >> cycle[j];
 
        for(int j = 1; j <= n; ++j)
            if(!memo[j])
                cnt += dfs(j, j, n);
        
        cout << cnt << endl;
        memset(cycle, 0, sizeof(cycle));
        memset(memo, 0, sizeof(memo));
    }
 
    return 0;
}