Add problem 332 - Reconstruct Itinerary

Author: anirudhology

problems/graph/reconstruct_itinerary.py

@@ -0,0 +1,26 @@
+import heapq
+from collections import defaultdict, deque
+from typing import List
+
+
+class ReconstructItinerary:
+    @staticmethod
+    def findItinerary(tickets: List[List[str]]) -> List[str]:
+        # Since we need to return the path in lexical order, we will
+        # use minHeap to store airports. Thus, we need a map that will
+        # connect the departure and arrival airports
+        flights = defaultdict(list)
+        # List to store the final path
+        path = deque()
+        # Process all flights to create the mappings
+        for departure, arrival in tickets:
+            heapq.heappush(flights[departure], arrival)
+
+        def dfs(departure_airport):
+            while flights[departure_airport]:
+                dfs(heapq.heappop(flights[departure_airport]))
+            path.appendleft(departure_airport)
+
+        # We start from JFK, hence we will perform DFS from there
+        dfs("JFK")
+        return list(path)

tests/graph/reconstruct_itinerary_test.py

@@ -0,0 +1,22 @@
+import unittest
+
+from problems.graph.reconstruct_itinerary import ReconstructItinerary
+
+
+class TestReconstructItinerary(unittest.TestCase):
+    def test_find_itinerary(self):
+        reconstruct_itinerary = ReconstructItinerary()
+
+        # Test case 1
+        tickets1 = [["MUC", "LHR"], ["JFK", "MUC"], ["SFO", "SJC"], ["LHR", "SFO"]]
+        expected1 = ["JFK", "MUC", "LHR", "SFO", "SJC"]
+        self.assertEqual(reconstruct_itinerary.findItinerary(tickets1), expected1)
+
+        # Test case 2
+        tickets2 = [["JFK", "SFO"], ["JFK", "ATL"], ["SFO", "ATL"], ["ATL", "JFK"], ["ATL", "SFO"]]
+        expected2 = ["JFK", "ATL", "JFK", "SFO", "ATL", "SFO"]
+        self.assertEqual(reconstruct_itinerary.findItinerary(tickets2), expected2)
+
+
+if __name__ == "__main__":
+    unittest.main()