Solution of Reconstruct Itenary

Author: Garvit244

300-400q/332.py

@@ -0,0 +1,52 @@
+'''
+	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:
+
+	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"].
+	All airports are represented by three capital letters (IATA code).
+	You may assume all tickets form at least one valid itinerary.
+	Example 1:
+
+	Input: tickets = [["MUC", "LHR"], ["JFK", "MUC"], ["SFO", "SJC"], ["LHR", "SFO"]]
+	Output: ["JFK", "MUC", "LHR", "SFO", "SJC"]
+'''
+
+from collections import defaultdict
+class Solution(object):
+    def findItinerary(self, tickets):
+        """
+        :type tickets: List[List[str]]
+        :rtype: List[str]
+        """
+        n = len(tickets)
+        trips = defaultdict(list)
+        for x in tickets:
+            trips[x[0]].append(x[1])
+        for x in trips:
+            trips[x].sort()
+        iter = ["JFK"]
+        
+        def dfs(curr_iter):
+            if len(curr_iter) == n+1: 
+                return curr_iter
+            curr_stop = curr_iter[-1]
+            
+            if trips[curr_stop] == []: 
+                return None
+            
+            next_stops = trips[curr_stop]
+            i = 0
+            for stop in next_stops:
+                curr_iter.append(stop)
+                del trips[curr_stop][i]
+                
+                if dfs(curr_iter): 
+                    return curr_iter
+                
+                curr_iter.pop()
+                trips[curr_stop].insert(i, stop)
+                i += 1
+            return None
+        
+        return dfs(iter)  

README.md

@@ -13,6 +13,7 @@ Python solution of problems from [LeetCode](https://leetcode.com/).
 |350|[Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | [Python](./300-400q/350.py)|Easy|
 |347|[Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/) | [Python](./300-400q/347.py)|Medium|
 |334|[Increasing Triplet Subsequence](https://leetcode.com/problems/increasing-triplet-subsequence/) | [Python](./300-400q/334.py)|Medium|
+|332|[Reconstruct Itinerary](https://leetcode.com/problems/reconstruct-itinerary/)|[Python](./300-400q/332.py)|Medium|
 |329|[Longest Increasing Path in a Matrix](https://leetcode.com/problems/longest-increasing-path-in-a-matrix/) | [Python](./300-400q/329.py)|Medium|
 |328|[Odd Even Linked List](https://leetcode.com/problems/odd-even-linked-list/) | [Python](./300-400q/328.py)|Easy|
 |326|[Power of Three](https://leetcode.com/problems/power-of-three/) | [Python](./300-400q/326.py)|Easy|