Depth-First Search in Python with Tests

Depth-First Search holds 200 problems (34 Easy, 132 Medium, 34 Hard). Generate any of them into the current directory with lcpy gen -n <number>.

#	Problem	Difficulty	Solution
79	Word Search	Medium	solution.py
94	Binary Tree Inorder Traversal	Easy	solution.py
98	Validate Binary Search Tree	Medium	solution.py
99	Recover Binary Search Tree	Medium	solution.py
100	Same Tree	Easy	solution.py
101	Symmetric Tree	Easy	solution.py
104	Maximum Depth of Binary Tree	Easy	solution.py
110	Balanced Binary Tree	Easy	solution.py
111	Minimum Depth of Binary Tree	Easy	solution.py
112	Path Sum	Easy	solution.py
113	Path Sum II	Medium	solution.py
114	Flatten Binary Tree to Linked List	Medium	solution.py
116	Populating Next Right Pointers In Each Node	Medium	solution.py
117	Populating Next Right Pointers in Each Node II	Medium	solution.py
124	Binary Tree Maximum Path Sum	Hard	solution.py
129	Sum Root to Leaf Numbers	Medium	solution.py
130	Surrounded Regions	Medium	solution.py
133	Clone Graph	Medium	solution.py
144	Binary Tree Preorder Traversal	Easy	solution.py
145	Binary Tree Postorder Traversal	Easy	solution.py
156	Binary Tree Upside Down	Medium	solution.py
199	Binary Tree Right Side View	Medium	solution.py
200	Number of Islands	Medium	solution.py
207	Course Schedule	Medium	solution.py
210	Course Schedule II	Medium	solution.py
211	Design Add and Search Words Data Structure	Medium	solution.py
226	Invert Binary Tree	Easy	solution.py
230	Kth Smallest Element in a BST	Medium	solution.py
235	Lowest Common Ancestor of a Binary Search Tree	Medium	solution.py
236	Lowest Common Ancestor of a Binary Tree	Medium	solution.py
250	Count Univalue Subtrees	Medium	solution.py
257	Binary Tree Paths	Easy	solution.py
261	Graph Valid Tree	Medium	solution.py
269	Alien Dictionary	Hard	solution.py
270	Closest Binary Search Tree Value	Easy	solution.py
272	Closest Binary Search Tree Value II	Hard	solution.py
285	Inorder Successor in BST	Medium	solution.py
297	Serialize and Deserialize Binary Tree	Hard	solution.py
298	Binary Tree Longest Consecutive Sequence	Medium	solution.py
302	Smallest Rectangle Enclosing Black Pixels	Hard	solution.py
310	Minimum Height Trees	Medium	solution.py
314	Binary Tree Vertical Order Traversal	Medium	solution.py
323	Number of Connected Components in an Undirected Graph	Medium	solution.py
329	Longest Increasing Path in a Matrix	Hard	solution.py
332	Reconstruct Itinerary	Hard	solution.py
333	Largest BST Subtree	Medium	solution.py
337	House Robber III	Medium	solution.py
339	Nested List Weight Sum	Medium	solution.py
341	Flatten Nested List Iterator	Medium	solution.py
364	Nested List Weight Sum II	Medium	solution.py
365	Water and Jug Problem	Medium	solution.py
366	Find Leaves of Binary Tree	Medium	solution.py
385	Mini Parser	Medium	solution.py
386	Lexicographical Numbers	Medium	solution.py
388	Longest Absolute File Path	Medium	solution.py
399	Evaluate Division	Medium	solution.py
404	Sum of Left Leaves	Easy	solution.py
417	Pacific Atlantic Water Flow	Medium	solution.py
419	Battleships in a Board	Medium	solution.py
426	Convert Binary Search Tree to Sorted Doubly Linked List	Medium	solution.py
428	Serialize and Deserialize N-ary Tree	Hard	solution.py
430	Flatten a Multilevel Doubly Linked List	Medium	solution.py
431	Encode N-ary Tree to Binary Tree	Hard	solution.py
437	Path Sum III	Medium	solution.py
449	Serialize and Deserialize BST	Medium	solution.py
463	Island Perimeter	Easy	solution.py
472	Concatenated Words	Hard	solution.py
490	The Maze	Medium	solution.py
499	The Maze III	Hard	solution.py
501	Find Mode in Binary Search Tree	Easy	solution.py
505	The Maze II	Medium	solution.py
508	Most Frequent Subtree Sum	Medium	solution.py
513	Find Bottom Left Tree Value	Medium	solution.py
514	Freedom Trail	Hard	solution.py
515	Find Largest Value in Each Tree Row	Medium	solution.py
529	Minesweeper	Medium	solution.py
530	Minimum Absolute Difference in BST	Easy	solution.py
536	Construct Binary Tree from String	Medium	solution.py
538	Convert BST to Greater Tree	Medium	solution.py
543	Diameter of Binary Tree	Easy	solution.py
545	Boundary of Binary Tree	Medium	solution.py
547	Number of Provinces	Medium	solution.py
549	Binary Tree Longest Consecutive Sequence II	Medium	solution.py
559	Maximum Depth of N-ary Tree	Easy	solution.py
563	Binary Tree Tilt	Easy	solution.py
565	Array Nesting	Medium	solution.py
572	Subtree of Another Tree	Easy	solution.py
582	Kill Process	Medium	solution.py
589	N-ary Tree Preorder Traversal	Easy	solution.py
590	N-ary Tree Postorder Traversal	Easy	solution.py
606	Construct String from Binary Tree	Medium	solution.py
617	Merge Two Binary Trees	Easy	solution.py
623	Add One Row to Tree	Medium	solution.py
637	Average of Levels in Binary Tree	Easy	solution.py
642	Design Search Autocomplete System	Hard	solution.py
652	Find Duplicate Subtrees	Medium	solution.py
653	Two Sum IV - Input is a BST	Easy	solution.py
655	Print Binary Tree	Medium	solution.py
662	Maximum Width of Binary Tree	Medium	solution.py
663	Equal Tree Partition	Medium	solution.py
666	Path Sum IV	Medium	solution.py
669	Trim a Binary Search Tree	Medium	solution.py
671	Second Minimum Node In a Binary Tree	Easy	solution.py
672	Bulb Switcher II	Medium	solution.py
676	Implement Magic Dictionary	Medium	solution.py
684	Redundant Connection	Medium	solution.py
685	Redundant Connection II	Hard	solution.py
687	Longest Univalue Path	Medium	solution.py
690	Employee Importance	Medium	solution.py
694	Number of Distinct Islands	Medium	solution.py
695	Max Area of Island	Medium	solution.py
711	Number of Distinct Islands II	Hard	solution.py
721	Accounts Merge	Medium	solution.py
733	Flood Fill	Easy	solution.py
737	Sentence Similarity II	Medium	solution.py
742	Closest Leaf in a Binary Tree	Medium	solution.py
743	Network Delay Time	Medium	solution.py
749	Contain Virus	Hard	solution.py
753	Cracking the Safe	Hard	solution.py
765	Couples Holding Hands	Hard	solution.py
776	Split BST	Medium	solution.py
778	Swim in Rising Water	Hard	solution.py
783	Minimum Distance Between BST Nodes	Easy	solution.py
785	Is Graph Bipartite?	Medium	solution.py
787	Cheapest Flights Within K Stops	Medium	solution.py
797	All Paths From Source to Target	Medium	solution.py
802	Find Eventual Safe States	Medium	solution.py
814	Binary Tree Pruning	Medium	solution.py
827	Making A Large Island	Hard	solution.py
834	Sum of Distances in Tree	Hard	solution.py
839	Similar String Groups	Hard	solution.py
841	Keys and Rooms	Medium	solution.py
851	Loud and Rich	Medium	solution.py
863	All Nodes Distance K in Binary Tree	Medium	solution.py
865	Smallest Subtree with all the Deepest Nodes	Medium	solution.py
872	Leaf-Similar Trees	Easy	solution.py
886	Possible Bipartition	Medium	solution.py
897	Increasing Order Search Tree	Easy	solution.py
924	Minimize Malware Spread	Hard	solution.py
928	Minimize Malware Spread II	Hard	solution.py
934	Shortest Bridge	Medium	solution.py
938	Range Sum of BST	Easy	solution.py
947	Most Stones Removed with Same Row or Column	Medium	solution.py
951	Flip Equivalent Binary Trees	Medium	solution.py
959	Regions Cut By Slashes	Medium	solution.py
965	Univalued Binary Tree	Easy	solution.py
968	Binary Tree Cameras	Hard	solution.py
971	Flip Binary Tree To Match Preorder Traversal	Medium	solution.py
979	Distribute Coins in Binary Tree	Medium	solution.py
987	Vertical Order Traversal of a Binary Tree	Hard	solution.py
988	Smallest String Starting From Leaf	Medium	solution.py
993	Cousins in Binary Tree	Easy	solution.py
1020	Number of Enclaves	Medium	solution.py
1028	Recover a Tree From Preorder Traversal	Hard	solution.py
1059	All Paths from Source Lead to Destination	Medium	solution.py
1088	Confusing Number II	Hard	solution.py
1102	Path With Maximum Minimum Value	Medium	solution.py
1110	Delete Nodes And Return Forest	Medium	solution.py
1120	Maximum Average Subtree	Medium	solution.py
1214	Two Sum BSTs	Medium	solution.py
1233	Remove Sub-Folders from the Filesystem	Medium	solution.py
1236	Web Crawler	Medium	solution.py
1245	Tree Diameter	Medium	solution.py
1254	Number of Closed Islands	Medium	solution.py
1267	Count Servers that Communicate	Medium	solution.py
1273	Delete Tree Nodes	Medium	solution.py
1325	Delete Leaves With a Given Value	Medium	solution.py
1361	Validate Binary Tree Nodes	Medium	solution.py
1367	Linked List in Binary Tree	Medium	solution.py
1376	Time Needed to Inform All Employees	Medium	solution.py
1443	Minimum Time to Collect All Apples in a Tree	Medium	solution.py
1448	Count Good Nodes in Binary Tree	Medium	solution.py
1457	Pseudo-Palindromic Paths in a Binary Tree	Medium	solution.py
1462	Course Schedule IV	Medium	solution.py
1466	Reorder Routes to Make All Paths Lead to the City Zero	Medium	solution.py
1490	Clone N-ary Tree	Medium	solution.py
1506	Find Root of N-Ary Tree	Medium	solution.py
1522	Diameter of N-Ary Tree	Medium	solution.py
1530	Number of Good Leaf Nodes Pairs	Medium	solution.py
1568	Minimum Number of Days to Disconnect Island	Hard	solution.py
1631	Path With Minimum Effort	Medium	solution.py
1905	Count Sub Islands	Medium	solution.py
1993	Operations on Tree	Medium	solution.py
2092	Find All People With Secret	Hard	solution.py
2096	Step-By-Step Directions From a Binary Tree Node to Another	Medium	solution.py
2101	Detonate the Maximum Bombs	Medium	solution.py
2127	Maximum Employees to Be Invited to a Meeting	Hard	solution.py
2331	Evaluate Boolean Binary Tree	Easy	solution.py
2359	Find Closest Node to Given Two Nodes	Medium	solution.py
2415	Reverse Odd Levels of Binary Tree	Medium	solution.py
2467	Most Profitable Path in a Tree	Medium	solution.py
2477	Minimum Fuel Cost to Report to the Capital	Medium	solution.py
2492	Minimum Score of a Path Between Two Cities	Medium	solution.py
2493	Divide Nodes Into the Maximum Number of Groups	Hard	solution.py
2641	Cousins in Binary Tree II	Medium	solution.py
2658	Maximum Number of Fish in a Grid	Medium	solution.py
2685	Count the Number of Complete Components	Medium	solution.py
2872	Maximum Number of K-Divisible Components	Hard	solution.py
3203	Find Minimum Diameter After Merging Two Trees	Hard	solution.py
3481	Apply Substitutions	Medium	solution.py

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Depth-First Search in Python with Tests