229. 바이러스

백준

1. DFS

정해

import sys
input = sys.stdin.readline

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

for _ in range(m):
    a, b = map(int, input().split())
    graph[a].append(b)
    graph[b].append(a)


def dfs(x):
    for i in graph[x]:
        if i not in visit:
            visit.append(i)
            dfs(i)


dfs(1)
print(len(visit) - 1)

• 양방향으로 연결해서 풀지 않으면 틀린다.

틀렸습니다

import sys
input = sys.stdin.readline

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

for _ in range(m):
    a, b = map(int, input().split())
    graph[a].append(b)


def dfs(x):
    for i in graph[x]:
        if i not in visit:
            visit.append(i)
            dfs(i)


dfs(1)
print(len(visit))