백준 11725번 - 트리의 부모 찾기

# 입력
import sys
n = int(sys.stdin.readline().strip())
graph = {}
for _ in range(n-1):
  a,b = map(int, sys.stdin.readline().split())
  if a in graph:
    graph[a].append(b)
  else:
    graph[a] = [b]
  if b in graph:
    graph[b].append(a)
  else:
    graph[b] = [a]  
visitedList = [False]*n
parent = {}

# 처리
def BFS(graph, node, visitedList):
  from collections import deque
  queue = deque([node])
  visitedList[node-1] = True

  while queue:
    temp = queue.popleft()
    for i in graph[temp]:
      if not visitedList[i-1]:
        queue.append(i)
        visitedList[i-1] = True
        parent[i] = temp

BFS(graph, 1, visitedList)
for i in sorted(parent.items()):
  print(i[1])