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Solution: Reconstruct Itinerary

Explore how to reconstruct an itinerary from a list of airline tickets starting at JFK by applying graph theory and Hierholzer's algorithm. Understand how to use depth-first search and sorting to find an Eulerian path covering all flights once, ensuring the itinerary is in lexical order. This lesson guides you through implementing and analyzing the solution efficiently.

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Statement

Given a list of airline tickets where tickets[i] = [fromi, toi] represent a departure airport and an arrival airport of a single flight, reconstruct the itinerary in the correct order and return it.

The person who owns these tickets always starts their journey from "JFK". Therefore, the itinerary must begin with "JFK". If there are multiple valid itineraries, you should prioritize the one with the smallest lexical ordeLexicographical order is a sorting arrangement similar to how words are arranged in a dictionary. It compares items character by character, based on their order in the alphabet or numerical value.r when considering a single string.

  • For example, the itinerary ["JFK", "EDU"] has a smaller lexical order than ["JFK", "EDX"].

Note: You may assume all tickets form at least one valid itinerary. You must use all the tickets exactly once.

Constraints:

  • 1≤1 \leq tickets.length ≤300\leq 300

  • tickets[i].length =2= 2

  • fromi ...