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:

• $1 \leq$ tickets.length $\leq 300$

• tickets[i].length $= 2$

• fromi.length $= 3$

• toi.length $= 3$

• fromi $\neq$ toi

• fromi and toi consist of uppercase English letters.

The algorithm uses Hierholzer’s algorithmHierholzer's algorithm is a method for finding an Eulerian circuit (a cycle that visits every edge exactly once) in a graph. It starts from any vertex and follows edges until it returns to the starting vertex, forming a cycle. If there are any unvisited edges, it starts a new cycle from a vertex on the existing cycle that has unvisited edges and merges the cycles. The process continues until all edges are visited. to reconstruct travel itineraries from a list of airline tickets. This problem is like finding an ...