[백준 2606] 바이러스 (C++/Python)

C++)

#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#define MAX_NUM 101
using namespace std;

bool visited[MAX_NUM];

int main(void) {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);

	int n, m, x, y;

	cin >> n;
	cin >> m;

	vector<vector<int>> v(n+1);
	for (int i = 0; i < m; i++) {
		cin >> x >> y;

		v[x].push_back(y);
		v[y].push_back(x);
	}

	queue<int> q;
	visited[1] = true;
	q.push(1);

	int ans = 0;
	while (!q.empty()) {
		int cur = q.front();
		q.pop();

		for (int i = 0; i < v[cur].size(); i++) {
			int next = v[cur][i];

			if (!visited[next]) {
				visited[next] = true;
				q.push(next);
				ans++;
			}
		}
	}

	cout << ans;

	return 0;
}

 

 

 

Python)

import sys
from collections import deque

read = sys.stdin.readline

n = int(read().rstrip())
m = int(read().rstrip())

arr = [ [] for _ in range(n+1)]
visited = [False] * (n+1)

for _ in range(m):
    x, y = map(int, read().rstrip().split())

    arr[x].append(y)
    arr[y].append(x)

q = deque()
visited[1] = True
q.append(1)

ans = 0
while q:
    cur = q.popleft()

    for next in arr[cur]:
        if not visited[next]:
            visited[next] = True
            q.append(next)
            ans += 1

print(ans)