[백준] [Python] 2606번 바이러스 - BFS

https://www.acmicpc.net/problem/2606

2606번: 바이러스

 

 

Python

from collections import deque
import sys
input = sys.stdin.readline

n = int(input())
graph = [ [] for _ in range(n+1) ]

for _ in range(int(input())):
    s, e = map(int, input().split())
    # 양방향 그래프일 때
    graph[s].append(e)
    graph[e].append(s)


visit = [0]*(n+1)
visit[1] = 1
q = deque([1])

result = -1

while q:
    x = q.popleft()
    result += 1

    for val in graph[x]:
        if visit[val] == 0:
            q.append(val)
            visit[val] = 1


print(result)