# ---
# title: 332. Reconstruct Itinerary
# id: problem332
# author: Tian Jun
# date: 2020-10-31
# difficulty: Medium
# categories: Depth-first Search, Graph
# link: <https://leetcode.com/problems/reconstruct-itinerary/description/>
# hidden: true
# ---
# 
# Given a list of airline tickets represented by pairs of departure and arrival
# airports `[from, to]`, reconstruct the itinerary in order. All of the tickets
# belong to a man who departs from `JFK`. Thus, the itinerary must begin with
# `JFK`.
# 
# **Note:**
# 
#   1. If there are multiple valid itineraries, you should return the itinerary that has the smallest lexical order when read as a single string. For example, the itinerary `["JFK", "LGA"]` has a smaller lexical order than `["JFK", "LGB"]`.
#   2. All airports are represented by three capital letters (IATA code).
#   3. You may assume all tickets form at least one valid itinerary.
#   4. One must use all the tickets once and only once.
# 
# **Example 1:**
# 
#     
#     
#     Input:[["MUC", "LHR"], ["JFK", "MUC"], ["SFO", "SJC"], ["LHR", "SFO"]]
#     Output:["JFK", "MUC", "LHR", "SFO", "SJC"]
#     
# 
# **Example 2:**
# 
#     
#     
#     Input:[["JFK","SFO"],["JFK","ATL"],["SFO","ATL"],["ATL","JFK"],["ATL","SFO"]]
#     Output:["JFK","ATL","JFK","SFO","ATL","SFO"]
#     Explanation: Another possible reconstruction is ["JFK","SFO","ATL","JFK","ATL","SFO"].
#                  But it is larger in lexical order.
#     
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
