[백준] 2606번 바이러스 (파이썬)

2606번: 바이러스

 

코드

n = int(input())
m = int(input())
tree = list([] for _ in range(101))
count = list(0 for _ in range(101))

dfs_check = list(0 for _ in range(101))
dfs_answer = []

for _ in range(m):
    between = list(map(int, input().split()))
    tree[between[0]].append(between[1])
    tree[between[1]].append(between[0])
    count[between[0]] += 1
    count[between[1]] += 1

def dfs(p):
    if dfs_check[p] == 0:
        dfs_check[p] = 1
        dfs_answer.append(p)
        tree[p].sort()
        for i in range(count[p]):
            dfs(tree[p][i])

dfs(1)
print(len(dfs_answer)-1)