[c++] 백준 1976번 여행 가자 (유니온-파인드)

#include<iostream>
#include<stdio.h>
#include<cstring>
#include<string>
#include<cmath>
#include<algorithm>
#include<functional>
#include<cstdbool>
#include<stack>
#include<vector>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define INF 987654321
#define LINF 321321321321
#define MAX 1100
 
int parent[1001000];
int n,m;
 
 
void init() {
    for (int i = 1; i <= n; i++) {
        parent[i] = i;
    }
}
 
int Find(int s) {
 
    if (parent[s] == s)
        return s;
    return parent[s] = Find(parent[s]);
}
 
 
void Merge(int a, int b) {
 
    a = Find(a);
    b = Find(b);
 
    if (a < b) {
        parent[b] = a;
    }
    else
        parent[a] = b;
}
 
 
int main(void) {
    
    cin >> n >> m;
    init();
    int cities[1101];
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            int tmp;
            cin >> tmp;
            if (tmp) {
                Merge(i, j);
            }
        }
    }
    for (int i = 1; i <= m; i++) {
        cin >> cities[i];
    }
    bool flag = true;
    for (int i = 1; i < m; i++) {
        if (Find(cities[i])!= Find(cities[i+1]) ){
            flag = false;
            break;
        }
    }
    if (flag) {
        cout << "YES";
    }
    else
        cout << "NO";
 
    return 0;
}
 
 

출처: https://www.acmicpc.net/problem/1976

1976번: 여행 가자