[백준 2606] 바이러스 - Python

def bfs(startNode):
    queue=list()
    queue.append(startNode)
    visited[startNode]=True
    while queue:
        node = queue.pop(0)
        for i in range(1,computer_num+1):
            if visited[i]==False and graph[node][i] ==1:
                queue.append(i)
                visited[i]=True


computer_num = int(input())
linked_pairs = int(input())
graph = [[0]*(computer_num+1) for i in range(computer_num+1)]
visited = [False] * (computer_num + 1)

for i in range(linked_pairs):
    x,y = map(int,input().split())
    graph[x][y] = 1
    graph[y][x] = 1
cnt=0
bfs(1)
for i in range(1,computer_num+1):
    if visited[i] == True:
        cnt+=1
print(cnt-1)