How should I practice Reconstruct Itinerary?

Start by reading the full statement, solve the visible examples, then compare the pattern against related PhonePe online assessment problems in FastPrep.

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Reconstruct Itinerary

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Problem statement

You are given airline tickets represented as [from, to] pairs. Reconstruct the itinerary that uses every ticket exactly once.

The itinerary must start at "JFK". If multiple valid itineraries exist, return the lexicographically smallest itinerary when read as a single sequence of airport codes.

Function

findItinerary(tickets: String[][]) → String[]

Examples

Example 1

tickets = [["MUC","LHR"],["JFK","MUC"],["SFO","SJC"],["LHR","SFO"]]return = ["JFK","MUC","LHR","SFO","SJC"]

There is only one route that uses all tickets from JFK.

Example 2

tickets = [["JFK","SFO"],["JFK","ATL"],["SFO","ATL"],["ATL","JFK"],["ATL","SFO"]]return = ["JFK","ATL","JFK","SFO","ATL","SFO"]

Both choices from JFK can lead to valid routes, but the route beginning with ATL is lexicographically smaller.