题目：
题解：
class Solution:def findItinerary(self, tickets: List[List[str]]) -> List[str]:def dfs(curr: str):while vec[curr]:tmp = heapq.heappop(vec[curr])dfs(tmp)stack.append(curr)vec = collections.defaultdict(list)for depart, arrive in tickets:vec[depart].append(arrive)for key in vec:heapq.heapify(vec[key])stack = list()dfs("JFK")return stack[::-1]