leetcode

My solutions for LeetCode problems.

Usage

Running and testing locally in your machine

First, install dependencies:

npm install

To run tests with jest:

npm run test

To run tests and generate code coverage report:

npm run test:coverage

Submitting / Running in LeetCode

1. Find your problem in the problems folder.
2. Copy the solution.
3. Paste the code into LeetCode.
4. Hit the Run or Submit button.

Pro-tip: URL / Folder Structure

The folder structure in this repository resembles the URL for LeetCode's problems, e.g.:

LeetCode URL for Two Sum problem: https://leetcode.com/problems/two-sum

Folder structure in this repository: https://github.com/ecgan/leetcode/tree/master/problems/two-sum

Solutions

The listing below is sorted based on LeetCode #. If you are interested to see my latest solutions in chronological order, check out the releases page, or my code commits.

LeetCode #	Title	Difficulty	Topics
1	Two Sum	Easy	Array, hash table
33	Search in Rotated Sorted Array	Medium	Array, Binary Search
35	Search Insert Position	Easy	Array, binary search
49	Group Anagrams	Medium	Hash Table, String
53	Maximum Subarray	Easy	Array, Divide and Conquer, Dynamic Programming
55	Jump Game	Medium	Array, Greedy
60	Permutation Sequence	Medium	Math, Backtracking
62	Unique Paths	Medium	Array, Dynamic Programming
64	Minimum Path Sum	Medium	Array, Dynamic Programming
70	Climbing Stairs	Easy	Dynamic Programming
72	Edit Distance	Hard	String, Dynamic Programming
75	Sort Colors	Medium	Array, Two Pointers, Sort
96	Unique Binary Search Trees	Medium	Dynamic Programming, Tree
121	Best Time to Buy and Sell Stock	Easy	Array, Dynamic Programming
122	Best Time to Buy and Sell Stock II	Easy	Array, Greedy
124	Binary Tree Maximum Path Sum	Hard	Tree, Depth-first Search
129	Sum Root to Leaf Numbers	Medium	Tree, Depth-first Search
130	Surrounded Regions	Medium	Depth-first Search, Breadth-first Search, Union Find
136	Single Number	Easy	Hash table, bit manipulation
137	Single Number II	Medium	Bit Manipulation
146	LRU Cache	Medium	Design
155	Min Stack	Easy	Stack, Design
169	Majority Element	Easy	Array, Divide and Conquer, Bit Manipulation
189	Rotate Array	Easy	Array
198	House Robber	Easy	Dynamic Programming
200	Number of Islands	Medium	Depth-first Search, Breadth-first Search, Union Find
201	Bitwise AND of Numbers Range	Medium	Bit Manipulation
202	Happy Number	Easy	Hash Table, Math
207	Course Schedule	Medium	Depth-first Search, Breadth-first Search, Graph, Topological Sort
208	Implement Trie (Prefix Tree)	Medium	Design, Trie
212	Word Search II	Hard	Backtracking, Trie
221	Maximal Square	Medium	Dynamic Programming
222	Count Complete Tree Nodes	Medium	Binary Search, Tree
226	Invert Binary Tree	Easy	Tree
230	Kth Smallest Element in a BST	Medium	Binary Search, Tree
231	Power of Two	Easy	Math, Bit Manipulation
237	Delete Node in a Linked List	Easy	Linked List
238	Product of Array Except Self	Medium	Array
275	H-Index II	Medium	Binary Search
278	First Bad Version	Easy	Binary Search
279	Perfect Squares	Medium	Math, Dynamic Programming, Breadth-first Search
283	Move Zeroes	Easy	Array, Two Pointers
287	Find the Duplicate Number	Medium	Array, Two Pointers, Binary Search
303	Range Sum Query - Immutable	Easy	Dynamic Programming
328	Odd Even Linked List	Medium	Linked List
332	Reconstruct Itinerary	Medium	Depth-first Search, Graph
338	Counting Bits	Medium	Dynamic Programming, Bit Manipulation
344	Reverse String	Easy	Two Pointers, String
349	Intersection of Two Arrays	Easy	Hash table, two pointers, binary search, sort, set
350	Intersection of Two Arrays II	Easy	Hash Table, two pointers, binary search, sort
367	Valid Perfect Square	Easy	Math, Binary Search
368	Largest Divisible Subset	Medium	Math, Dynamic Programming
380	Insert Delete GetRandom O(1)	Medium	Array, Hash Table, Design
383	Ransom Note	Easy	String
387	First Unique Character in a String	Easy	Hash Table, String
392	Is Subsequence	Easy	Binary Search, Dynamic Programming, Greedy
402	Remove K Digits	Medium	Stack, Greedy
406	Queue Reconstruction by Height	Medium	Greedy
438	Find All Anagrams in a String	Medium	Hash Table
451	Sort Characters By Frequency	Medium	Hash Table, Heap
468	Validate IP Address	Medium	String
476	Number Complement	Easy	Bit Manipulation
518	Coin Change 2	Medium	-
525	Contiguous Array	Medium	Hash Table
528	Random Pick with Weight	Medium	Binary Search, Random
540	Single Element in a Sorted Array	Medium	-
543	Diameter of Binary Tree	Easy	Tree
560	Subarray Sum Equals K	Medium	Array, Hash Table
567	Permutation in String	Medium	Two Pointers, Sliding Window
678	Valid Parenthesis String	Medium	String
700	Search in a Binary Search Tree	Easy	Tree
714	Dungeon Game	Hard	Binary Search, Dynamic Programming
733	Flood Fill	Easy	Depth-first Search
746	Min Cost Climbing Stairs	Easy	Array, Dynamic Programming
771	Jewels and Stones	Easy	Hash Table
787	Cheapest Flights Within K Stops	Medium	Dynamic Programming, Heap, Breadth-first Search
844	Backspace String Compare	Easy	Two Pointers, Stack
876	Middle of the Linked List	Easy	Linked List
886	Possible Bipartition	Medium	Depth-first Search
901	Online Stock Span	Medium	Stack
918	Maximum Sum Circular Subarray	Medium	Array
973	K Closest Points to Origin	Medium	Divide and Conquer, Heap, Sort
986	Interval List Intersections	Medium	Two Pointers
993	Cousins in Binary Tree	Easy	Tree, Breadth-first Search
997	Find the Town Judge	Easy	Graph
1008	Construct Binary Search Tree from Preorder Traversal	Medium	Tree
1025	Divisor Game	Easy	Math, Dynamic Programming
1029	Two City Scheduling	Easy	Greedy
1035	Uncrossed Lines	Medium	Array
1044	Longest Duplicate Substring	Hard	Hash Table, Binary Search
1046	Last Stone Weight	Easy	Heap, Greedy
1143	Longest Common Subsequence	Medium	Dynamic Programming
1144	Decrease Elements To Make Array Zigzag	Medium	Array
1145	Binary Tree Coloring Game	Medium	Tree, depth-first search
1150	Check If a Number Is Majority Element in a Sorted Array	Easy	Array, binary search
1153	String Transforms Into Another String	Hard	Graph
1154	Day of the Year	Easy	Math
1160	Find Words That Can Be Formed by Characters	Easy	Array, hash table
1161	Maximum Level Sum of a Binary Tree	Medium	Graph
1162	As Far from Land as Possible	Medium	Breadth-first search, graph
1163	Last Substring in Lexicographical Order	Hard	String, suffix array
1165	Single-Row Keyboard	Easy	String
1167	Minimum Cost to Connect Sticks	Medium	Greedy
1170	Compare Strings by Frequency of the Smallest Character	Easy	Array, string
1177	Can Make Palindrome from Substring	Medium	Array, string
1184	Distance Between Bus Stops	Easy	Array
1185	Day of the Week	Easy	Array
1207	Unique Number of Occurrences	Easy	Hash table
1208	Get Equal Substrings Within Budget	Medium	Array, sliding window
1213	Intersection of Three Sorted Arrays	Easy	Hash table, two pointers
1214	Two Sum BSTs	Medium	Binary search tree
1217	Play with Chips	Easy	Array, math, greedy
1232	Check If It Is a Straight Line	Easy	Array, Math, Geometry
1243	Array Transformation	Easy	Array
1244	Design A Leaderboard	Medium	Hash table, sort, design
1247	Minimum Swaps to Make Strings Equal	Medium	String, greedy
1256	Encode Number	Medium	Math, bit manipulation
1260	Shift 2D Grid	Easy	Array
1261	Find Elements in a Contaminated Binary Tree	Medium	Hash table, tree
1271	Hexspeak	Easy	Math, string
1272	Remove Interval	Medium	Math, line sweep
1275	Find Winner on a Tic Tac Toe Game	Easy	Array
1276	Number of Burgers with No Waste of Ingredients	Medium	Math, greedy
1277	Count Square Submatrices with All Ones	Medium	Array, Dynamic Programming
1313	Decompress Run-Length Encoded List	Easy	Array
1314	Matrix Block Sum	Medium	Dynamic programming
1317	Convert Integer to the Sum of Two No-Zero Integers	Easy	Math
1342	Number of Steps to Reduce a Number to Zero	Easy	Bit manipulation
1343	Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold	Medium	Array
1344	Angle Between Hands of a Clock	Medium	Math
1346	Check If N and Its Double Exist	Easy	Array
1347	Minimum Number of Steps to Make Two Strings Anagram	Medium	String
1348	Tweet Counts Per Frequency	Medium	Design
1356	Sort Integers by The Number of 1 Bits	Easy	Sort, bit manipulation
1357	Apply Discount Every n Orders	Medium	Design
1358	Number of Substrings Containing All Three Characters	Medium	String
1360	Number of Days Between Two Dates	Easy	-
1361	Validate Binary Tree Nodes	Medium	Graph
1362	Closest Divisors	Medium	Math
1370	Increasing Decreasing String	Easy	String, sort
1374	Generate a String With Characters That Have Odd Counts	Easy	String
1385	Find the Distance Value Between Two Arrays	Easy	Array
1386	Cinema Seat Allocation	Medium	Array, Greedy
1387	Sort Integers by The Power Value	Medium	Sort, Graph
1389	Create Target Array in the Given Order	Easy	Array
1390	Four Divisors	Medium	Math
1401	Circle and Rectangle Overlapping	Medium	Geometry
1404	Number of Steps to Reduce a Number in Binary Representation to One	Medium	String, Bit Manipulation
1413	Minimum Value to Get Positive Step by Step Sum	Easy	Array
1417	Reformat The String	Easy	String
1418	Display Table of Food Orders in a Restaurant	Medium	Hash Table
1419	Minimum Number of Frogs Croaking	Medium	String
1426	Counting Elements	-	-
1427	Perform String Shifts	-	-
1428	Leftmost Column with at Least a One	-	-
1429	First Unique Number	-	-
1430	Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree	-	-
1475	Final Prices With a Special Discount in a Shop	Easy	Array
1476	Subrectangle Queries	Medium	Array
1480	Running Sum of 1d Array	Easy	Array
1481	Least Number of Unique Integers after K Removals	Medium	Array, Sort
1491	Average Salary Excluding the Minimum and Maximum Salary	Easy	Array, Sort
1492	The kth Factor of n	Medium	Math
1493	Longest Subarray of 1's After Deleting One Element	Medium	Array
1572	Matrix Diagonal Sum	Easy	Array
1574	Shortest Subarray to be Removed to Make Array Sorted	Medium	Array, Binary Search
1576	Replace All ?'s to Avoid Consecutive Repeating Characters	Easy	String
1577	Number of Ways Where Square of Number Is Equal to Product of Two Numbers	Medium	Hash Table, Math
1578	Minimum Deletion Cost to Avoid Repeating Letters	Medium	Greedy
1603	Design Parking System	Easy	Design
1604	Alert Using Same Key-Card Three or More Times in a One Hour Period	Medium	String, Ordered Map
1608	Special Array With X Elements Greater Than or Equal X	Easy	Array
1609	Even Odd Tree	Medium	Tree

Questions / Issues

If you have any question, feel free to open a GitHub issue and reach out to me.