Python solutions of LeetCode problems.

       

Project on summer pause :)

Introduction

In this repository provided my Python solutions of LeetCode problems.

• I highly recommend you to try and solve problems yourself before look at the solutions here.
• Solutions and approaches may be not optimal (I'm learning and practicing DSA & committing my solutions).
• All Solutions here are in Python 3.

LeetCoding Challenges

2020:

• April LeetCoding Challenge - 28/30
• August LeetCoding Challenge - 31/31
• September LeetCoding Challenge - 30/30
• November LeetCoding Challenge - 24/30
• December LeetCoding Challenge - 27/31

2021:

• January LeetCoding Challenge - 27/31
• February LeetCoding Challenge - 23/28
• March LeetCoding Challenge - 23/31
• April LeetCoding Challenge - 23/30
• May LeetCoding Challenge - 17/31
• June LeetCoding Challenge - 10/30

Solutions

P.S. If you like this, please leave me a star. ★

№	Title	Solution	Difficulty	Note
1.	Two Sum	Python	Easy
1.	Two Sum	Python	Easy	optimized soln
2.	Add Two Numbers	Python	Medium	Linked List + brute force
3.	Longest Substring Without Repeating Characters	Python	Medium	Kinda brute force
4.	Median of Two Sorted Arrays	Python	Hard
5.	Longest Palindromic Substring	Python	Medium	Brute Force
7.	Reverse Integer	Python	Easy
9.	Palindrome Number	Python	Easy	Without converting integer into string
11.	Container With Most Water	Python	Medium	Two Pointers
12.	Integer to Roman	Python	Medium
13.	Roman to Integer	Python	Easy
14.	Longest Common Prefix	Python	Easy
15.	3Sum	Python	Medium	Brute Force
16.	3Sum Closest	Python	Medium	Brute Force
17.	Letter Combinations of a Phone Number	Python	Medium	DFS, Recursion
19.	Remove Nth Node From End of List	Python	Medium	Stack
20.	Valid Parentheses	Python	Easy	Brute Force
20.	Valid Parentheses	Python	Easy	Stack
21.	Merge Two Sorted Lists	Python	Easy	Linked List
23.	Merge k Sorted Lists	Python	Hard	Linked List, not exactly what was aked
24.	Swap Nodes in Pairs	Python	Medium	Linked List
25.	Reverse Nodes in k-Group	Python	Hard	Linked List, Stack
26.	Remove Duplicates from Sorted Array	Python	Easy	Several solutions in one file
27.	Remove Element	Python	Easy
29.	Divide Two Integers	Python	Medium
33.	Search in Rotated Sorted Array	Python	Medium
34.	Find First and Last Position of Element in Sorted Array	Python	Medium	Binary Search
34.	Find First and Last Position of Element in Sorted Array	Python	Medium
35.	Search Insert Position	Python	Easy	Binary Search
36.	Valid Sudoku	Python	Medium	Brute Force, set, list
41.	First Missing Positive	Python	Hard
46.	Permutations	Python	Medium	Itertools
47.	Permutations II	Python	Medium	Itertools
48.	Rotate Image	Python	Medium
49.	Group Anagrams	Python	Medium
50.	Pow(x, n)	Python	Medium	Recursion
53.	Maximum Subarray	Python	Easy
54.	Spiral Matrix	Python	Medium
55.	Jump Game	Python	Medium
56.	Merge Intervals	Python	Medium
57.	Insert Interval	Python	Hard
58.	Length of Last Word	Python	Easy	List
58.	Length of Last Word	Python	Easy	String
59.	Spiral Matrix II	Python	Medium	spaghetti
61.	Rotate List	Python	Medium	Linked List
63.	Unique Paths II	Python	Medium	DP
64.	Minimum Path Sum	Python	Medium
66.	Plus One	Python	Easy
67.	Add Binary	Python	Easy
71.	Simplify Path	Python	Medium	Stack
73.	Set Matrix Zeroes	Python	Medium	set()
74.	Search a 2D Matrix	Python	Medium	Binary Search
75.	Sort Colors	Python	Medium	Bubble Sort
75.	Sort Colors	Python	Medium	Selection Sort
75.	Sort Colors	Python	Medium	Insertion Sort
75.	Sort Colors	Python	Medium	Quick Sort
75.	Sort Colors	Python	Medium	Merge Sort
78.	Subsets	Python	Medium	itertools.combinations()
80.	Remove Duplicates from Sorted Array II	Python	Medium
81.	Search in Rotated Sorted Array II	Python	Medium
82.	Remove Duplicates from Sorted List II	Python	Medium	Linked List
83.	Remove Duplicates from Sorted List	Python	Easy	Linked List
86.	Partition List	Python	Medium	Linked List
88.	Merge Sorted Array	Python	Easy	Two solutions
92.	Reverse Linked List II	Python	Medium	Stack, Linked List
94.	Binary Tree Inorder Traversal	Python	Medium	Binary Tree, Recursion
98.	Validate Binary Search Tree	Python	Medium	Binary Tree, Recursion
98.	Validate Binary Search Tree	Python	Medium	Binary Tree, Recursion, another valid. approach
100.	Same Tree	Python	Easy	Binary Tree (preorder), Recursion
101.	Symmetric Tree	Python	Easy	BFS, iteratively
102.	Binary Tree Level Order Traversal	Python	Medium	BFS, Overcode
103.	Binary Tree Zigzag Level Order Traversal	Python	Medium	BFS
104.	Maximum Depth of Binary Tree	Python	Easy	Binary Tree, Recursion
107.	Binary Tree Level Order Traversal II	Python	Easy	BFS
110.	Balanced Binary Tree	Python	Easy	DFS, Recursion
111.	Minimum Depth of Binary Tree	Python	Easy	Binary Tree, Recursion
112.	Path Sum	Python	Easy	Binary Tree, Recursion
114.	Flatten Binary Tree to Linked List	Python	Medium	DFS, preorder
116.	Populating Next Right Pointers in Each Node	Python	Medium	BFS
117.	Populating Next Right Pointers in Each Node II	Python	Medium	BFS, same as 116
118.	Pascal's Triangle	Python	Easy
119.	Pascal's Triangle II	Python	Easy
120.	Triangle	Python	Medium
121.	Best Time to Buy and Sell Stock	Python	Easy
122.	Best Time to Buy and Sell Stock II	Python	Easy
123.	Best Time to Buy and Sell Stock III	Python	Hard
124.	Binary Tree Maximum Path Sum	Python	Hard
125.	Valid Palindrome	Python	Easy	Two pointers from start & end
125.	Valid Palindrome	Python	Easy	Re.findall and left half == rev. right half
125.	Valid Palindrome	Python	Easy	Re.sub and s == reversed s
128.	Longest Consecutive Sequence	Python	Medium
129.	Sum Root to Leaf Numbers	Python	Medium	DFS
134.	Gas Station	Python	Medium
136.	Single Number	Python	Easy
137.	Single Number II	Python	Medium	Brute Force
138.	Copy List with Random Pointer	Python	Medium	Linked List
139.	Word Break	Python	Medium	Watched how to complete
141.	Linked List Cycle	Python	Easy	Linked List, Brute Force
141.	Linked List Cycle	Python	Easy	Linked List, set()
142.	Linked List Cycle II	Python	Medium	Linked List, set()
143.	Reorder List	Python	Medium	Linked List, Stack
144.	Binary Tree Preorder Traversal	Python	Medium	Binary Tree, Recursion
145.	Binary Tree Postorder Traversal	Python	Hard	Binary Tree, Recursion
146.	LRU Cache	Python	Medium
147.	Insertion Sort List	Python	Medium	Not exactly what asked, Linked List, Binary Search
148.	Sort List	Python	Medium	Linked List, Brute Force
150.	Evaluate Reverse Polish Notation	Python	Medium	Stack
152.	Maximum Product Subarray	Python	Medium	DP
153.	Find Minimum in Rotated Sorted Array	Python	Medium	For loop
153.	Find Minimum in Rotated Sorted Array	Python	Medium	Binary Search
154.	Find Minimum in Rotated Sorted Array II	Python	Hard	For loop
155.	Min Stack	Python	Easy
160.	Intersection of Two Linked Lists	Python	Easy	Linked List
162.	Find Peak Element	Python	Medium
164.	Maximum Gap	Python	Hard
165.	Compare Version Numbers	Python	Medium
167.	Two Sum II - Input array is sorted	Python	Easy
168.	Excel Sheet Column Title	Python	Easy
171.	Excel Sheet Column Number	Python	Easy
172.	Factorial Trailing Zeroes	Python	Easy	Brute Force
173.	Binary Search Tree Iterator	Python	Medium	inorder
179.	Largest Number	Python	Medium	Bubble sort
191.	Number of 1 Bits	Python	Easy
198.	House Robber	Python	Easy
199.	Binary Tree Right Side View	Python	Medium	BFS
200.	Number of Islands	Python	Medium
201.	Bitwise AND of Numbers Range	Python	Medium
202.	Happy Number	Python	Easy
203.	Remove Linked List Elements	Python	Easy	Linked List
204.	Count Primes	Python	Easy
205.	Isomorphic Strings	Python	Easy	Dictionary
206.	Reverse Linked List	Python	Easy	Linked List, brute force
206.	Reverse Linked List	Python	Easy	Linked List
208.	Implement Trie (Prefix Tree)	Python	Medium	Trie, 1st time all by myself
209.	Minimum Size Subarray Sum	Python	Medium
211.	Add and Search Word - Data structure design	Python	Medium	Need to resolve
215.	Kth Largest Element in an Array	Python	Medium	sorted()
216.	Combination Sum III	Python	Medium	Backtracking
217.	Contains Duplicate	Python	Easy	Dictionary
219.	Contains Duplicate II	Python	Easy	Dictionary, enumerate
220.	Contains Duplicate III	Python	Medium	Two pointers?
221.	Maximal Square	Python	Medium
222.	Count Complete Tree Nodes	Python	Medium	Recursion
225.	Implement Stack using Queues	Python	Easy	List
226.	Invert Binary Tree	Python	Easy	Recursion
227.	Basic Calculator II	Python	Medium	Queue, Brute Force
228.	Summary Ranges	Python	Medium	Two Pointers
229.	Majority Element II	Python	Medium	Brute Force
229.	Majority Element II	Python	Medium	a bit optimized
230.	Kth Smallest Element in a BST	Python	Medium	Recursion, inorder, brute force
232.	Implement Queue using Stacks	Python	Easy	List
234.	Palindrome Linked List	Python	Easy	Linked List
237.	Delete Node in a Linked List	Python	Easy	Linked List
238.	Product of Array Except Self	Python	Medium
240.	Search a 2D Matrix II	Python	Medium	Binary Search
242.	Valid Anagram	Python	Easy
257.	Binary Tree Paths	Python	Easy	Binary Tree (preorder), Recursion
258.	Add Digits	Python	Easy
260.	Single Number III	Python	Medium	Set
268.	Missing Number	Python	Easy
274.	H-Index	Python	Medium
275.	H-Index II	Python	Medium	Solution for problem #274 worked fine
283.	Move Zeroes	Python	Easy
284.	Peeking Iterator	Python	Medium
289.	Game of Life	Python	Medium
290.	Word Pattern	Python	Easy	Dictionary, enumerate
295.	Find Median from Data Stream	Python	Hard	Brute Force
295.	Find Median from Data Stream	Python	Hard	Binary Search
297.	Serialize and Deserialize Binary Tree	Python	Hard	BFS
299.	Bulls and Cows	Python	Easy
304.	Range Sum Query 2D - Immutable	Python	Medium	Brute force
304.	Range Sum Query 2D - Immutable	Python	Medium	A bit optimized but still brute force
307.	Range Sum Query - Mutable	[Python](/Medium/307.RangeSumQuery - Mutable.py)	Medium
318.	Maximum Product of Word Lengths	Python	Medium	Brute Force
326.	Power of Three	Python	Easy	while
328.	Odd Even Linked List	Python	Medium	Linked List
329.	Longest Increasing Path in a Matrix	Python	Hard	DFS, LRU_cache, Brute Force
334.	Increasing Triplet Subsequence	Python	Medium	Brute Force
341.	Flatten Nested List Iterator	Python	Medium
342.	Power of Four	Python	Easy	Brute Force
342.	Power of Four	Python	Easy	Bitwise
344.	Reverse String	Python	Easy
345.	Reverse Vowels of a String	Python	Easy	String, in-place, slow
345.	Reverse Vowels of a String	Python	Easy	List, fast, ~x4
347.	Top K Frequent Elements	Python	Medium	Hash Table
355.	Design Twitter	Python	Medium	May be improved with collections
376.	Wiggle Subsequence	Python	Medium
378.	Kth Smallest Element in a Sorted Matrix	Python	Medium	Converted matrix into list
380.	Insert Delete GetRandom O(1)	Python	Medium	not O(1), Brute force
381.	Insert Delete GetRandom O(1) - Duplicates allowed	Python	Hard	not O(1), Brute force
382.	Linked List Random Node	Python	Medium	random.choice()
384.	Shuffle an Array	Python	Medium	random.sample()
387.	First Unique Character in a String	Python	Easy	Brute Force
387.	First Unique Character in a String	Python	Easy	Dictionary, enumerate
389.	Find the Difference	Python	Easy	set, .count()
389.	Find the Difference	Python	Easy	.replace()
392.	Is Subsequence	Python	Easy
394.	Decode String	Python	Medium	Stack
395.	Longest Substring with At Least K Repeating Characters	Python	Medium	collections, Recursion
398.	Random Pick Index	Python	Medium	random.choice()
399.	Evaluate Division	Python	Medium	God bless youtube
402.	Remove K Digits	Python	Medium	Stack
404.	Sum of Left Leaves	Python	Easy	Recursion, preorder
409.	Longest Palindrome	Python	Easy
412.	Fizz Buzz	Python	Easy
421.	Maximum XOR of Two Numbers in an Array	Python	Medium	googled soln
423.	Reconstruct Original Digits from English	Python	Medium
429.	N-ary Tree Level Order Traversal	Python	Medium	BFS
432.	All O`one Data Structure	Python	Hard	Dictionary as Data Structure
435.	Non-overlapping Intervals	Python	Medium	lambda
436.	Find Right Interval	Python	Medium	Brute Force
437.	Path Sum III	Python	Medium	DFS
441.	Arranging Coins	Python	Easy	Iteratively
442.	Find All Duplicates in an Array	Python	Medium	set()
445.	Add Two Numbers II	Python	Medium	converted to int and back to Linked List
449.	Serialize and Deserialize BST	Python	Medium	Complicated solution - resolve
450.	Delete Node in a BST	Python	Medium	Binary Search Tree, Recursion
451.	Sort Characters By Frequency	Python	Medium	Surprisingly fast solution
452.	Minimum Number of Arrows to Burst Balloons	Python	Medium
454.	4Sum II	Python	Medium	Dictionary
456.	132 Pattern	Python	Medium	Brute Force
458.	Poor Pigs	Python	Hard	math
459.	Repeated Substring Pattern	Python	Easy
462.	Minimum Moves to Equal Array Elements II	Python	Medium	median
468.	Validate IP Address	Python	Medium
470.	Implement Rand10() Using Rand7()	Python	Medium	'Invented the wheel'
476.	Number Complement	Python	Easy
478.	Generate Random Point in a Circle	Python	Medium
495.	Teemo Attacking	Python	Medium
496.	Next Greater Element I	Python	Easy	Brute force - resolve
497.	Random Point in Non-overlapping Rectangles	Python	Medium	Random, Bisect
498.	Diagonal Traverse	Python	Medium	Used theory from GfG.com
500.	Keyboard Row	Python	Easy	Dictionary
501.	Find Mode in Binary Search Tree	Python	Easy	Recursion
503.	Next Greater Element II	Python	Medium	Brute Force
509.	Fibonacci Number	Python	Easy	List
509.	Fibonacci Number	Python	Easy	Dictionary
509.	Fibonacci Number	Python	Easy	Used two variables n1 & n2
513.	Find Bottom Left Tree Value	Python	Medium	BFS
515.	Find Largest Value in Each Tree Row	Python	Medium	BFS
520.	Detect Capital	Python	Easy	Built-in functions
524.	Longest Word in Dictionary through Deleting	Python	Medium
525.	Contiguous Array	Python	Medium
526.	Beautiful Arrangement	Python	Medium	DFS, brute force
530.	Minimum Absolute Difference in BST	Python	Easy	Bad solution - resolve
532.	K-diff Pairs in an Array	Python	Medium	Brute force
535.	Encode and Decode TinyURL	Python	Medium	Dictionary as db, random generated url
538.	Convert BST to Greater Tree	Python	Easy	DFS, recursion
540.	Single Element in a Sorted Array	Python	Medium	Binary Search
543.	Diameter of Binary Tree	Python	Easy
554.	Brick Wall	Python	Medium	Hash Table
556.	Next Greater Element III	Python	Medium
559.	Maximum Depth of N-ary Tree	Python	Easy	BFS
560.	Subarray Sum Equals K	Python	Medium
563.	Binary Tree Tilt	Python	Easy	Binary Tree, postorder, overcode
566.	Reshape the Matrix	Python	Easy	Brute Force
575.	Distribute Candies	Python	Easy
581.	Shortest Unsorted Continuous Subarray	Python	Medium
589.	N-ary Tree Preorder Traversal	Python	Easy	Recursion
590.	N-ary Tree Postorder Traversal	Python	Easy	Recursion
593.	Valid Square	Python	Medium
594.	Longest Harmonious Subsequence	Python	Easy	defaultdict
594.	Longest Harmonious Subsequence	Python	Easy	Counter
599.	Minimum Index Sum of Two Lists	Python	Easy	Dictionary, enumerate
605.	Can Place Flowers	Python	Easy	simple counter
609.	Find Duplicate File in System	Python	Medium	Dictionary, nested for loop, list comprehension
622.	Design Circular Queue	Python	Medium	Implement through list (first time)
623.	Add One Row to Tree	Python	Medium	BFS
637.	Average of Levels in Binary Tree	Python	Easy	Binary Tree, Recursion
641.	Design Circular Deque	Python	Medium	Need to resolve without use of builtin functions (first time)
645.	Set Mismatch	Python	Easy	collections.Counter
647.	Palindromic Substrings	Python	Medium
653.	Two Sum IV - Input is a BST	Python	Easy	Brute Force - resolve
654.	Maximum Binary Tree	Python	Medium	DFS, Recursion
657.	Robot Return to Origin	Python	Easy	Dictionary
658.	Find K Closest Elements	Python	Medium	Binary Search
665.	Non-decreasing Array	Python	Easy	Brute Force
667.	Beautiful Arrangement II	Python	Medium
671.	Second Minimum Node In a Binary Tree	Python	Easy	DFS, Recursion
674.	Longest Continuous Increasing Subsequence	Python	Easy	simple counter
677.	Map Sum Pairs	Python	Medium	Trie
678.	Valid Parenthesis String	Python	Medium
682.	Baseball Game	Python	Easy
690.	Employee Importance	Python	Easy	BFS
695.	Max Area of Island	Python	Medium	DFS
696.	Count Binary Substrings	Python	Easy
700.	Search in a Binary Search Tree	Python	Easy	Binary Search Tree, Recursion
701.	Insert into a Binary Search Tree	Python	Medium	Binary Search Tree, Recursion
703.	Kth Largest Element in a Stream	Python	Easy	brute force
705.	Design HashSet	Python	Easy	list as a set
706.	Design HashMap	Python	Easy	list
707.	Design Linked List	Python	Medium	Linked List, first time
709.	To Lower Case	Python	Easy	Two solutions. 1st w. in place changes, 2nd saves in var
713.	Subarray Product Less Than K	Python	Medium	Two pointers
720.	Longest Word in Dictionary	Python	Easy	Trie
722.	Remove Comments	Python	Medium	String
728.	Self Dividing Numbers	Python	Easy	Math
729.	My Calendar I	Python	Medium	Limked List, Dictionary
735.	Asteroid Collision	Python	Medium	Stack
744.	Find Smallest Letter Greater Than Target	Python	Easy	Binary Search
746.	Min Cost Climbing Stairs	Python	Easy	DP
754.	Reach a Number	Python	Medium	Math
763.	Partition Labels	Python	Medium	Brute Force - resolve
771.	Jewels and Stones	Python	Easy	while loop, for loop and list comprehension
775.	Global and Local Inversions	Python	Medium
785.	Is Graph Bipartite?	Python	Medium	Iteratively BFS, stack, XOR
791.	Custom Sort String	Python	Medium
804.	Unique Morse Code Words	Python	Easy	Dictionary
807.	Max Increase to Keep City Skyline	Python	Medium
811.	Subdomain Visit Count	Python	Easy	Dictionary
817.	Linked List Components	Python	Medium	Set
817.	Linked List Components	Python	Medium	List, 35 times slower
820.	Short Encoding of Words	Python	Medium	Brute Force
821.	Shortest Distance to a Character	Python	Easy	overcode
824.	Goat Latin	Python	Easy
832.	Flipping an Image	Python	Easy
832.	Flipping an Image	Python	Easy	.reverse()
835.	Image Overlap	Python	Medium	Brute Force
841.	Keys and Rooms	Python	Medium	BFS
844.	Backspace String Compare	Python	Easy
845.	Longest Mountain in Array	Python	Medium	one pass
849.	Maximize Distance to Closest Person	Python	Medium
852.	Peak Index in a Mountain Array	Python	Easy	List comprehension
852.	Peak Index in a Mountain Array	Python	Easy	Set
858.	Mirror Reflection	Python	Medium
859.	Buddy Strings	Python	Easy	Brute Force
865.	Smallest Subtree with all the Deepest Nodes	Python	Medium	DFS, Recursion
869.	Reordered Power of 2	Python	Medium	int to string
872.	Leaf-Similar Trees	Python	Easy	Recursion
876.	Middle of the Linked List	Python	Easy
880.	Decoded String at Index	Python	Medium
881.	Boats to Save People	Python	Medium	Two Pointers
884.	Uncommon Words from Two Sentences	Python	Easy	simple counter
890.	Find and Replace Pattern	Python	Medium	Dictionary
895.	Maximum Frequency Stack	Python	Hard
896.	Monotonic Array	Python	Easy
897.	Increasing Order Search Tree	Python	Easy	DFS, iteratively
900.	RLE Iterator	Python	Medium
905.	Sort Array By Parity	Python	Easy	List
908.	Smallest Range I	Python	Easy
910.	Smallest Range II	Python	Medium
911.	Online Election	Python	Medium	Binary Search
912.	Sort an Array	Python	Medium	sorted()
916.	Word Subsets	Python	Medium	collections.Counter, Dictionary
922.	Sort Array By Parity II	Python	Easy	Dictionary
922.	Sort Array By Parity II	Python	Easy	List
922.	Sort Array By Parity II	Python	Easy	Two Pointers
923.	3Sum With Multiplicity	Python	Medium	collections.Counter
929.	Unique Email Addresses	Python	Easy
933.	Number of Recent Calls	Python	Easy	Binary Search and rewrite list
933.	Number of Recent Calls	Python	Easy	while and rewrite list
933.	Number of Recent Calls	Python	Easy	while and .pop()
938.	Range Sum of BST	Python	Easy	Binary Search Tree
938.	Range Sum of BST	Python	Easy	Binary Search Tree, Optimized solution
941.	Valid Mountain Array	Python	Easy
946.	Validate Stack Sequences	Python	Medium	Stack
949.	Largest Time for Given Digits	Python	Easy	Itertools
952.	Largest Component Size by Common Factor	Python	Hard	Googled soln
953.	Verifying an Alien Dictionary	Python	Easy
961.	N-Repeated Element in Size 2N Array	Python	Easy	Brute Force
961.	N-Repeated Element in Size 2N Array	Python	Easy	Dictionary, a bit optimized
965.	Univalued Binary Tree	Python	Easy	Binary Tree, Recursion
966.	Vowel Spellchecker	Python	Medium	Dictionary
967.	Numbers With Same Consecutive Differences	Python	Medium	DFS
969.	Pancake Sorting	Python	Medium	sort
970.	Powerful Integers	Python	Medium	nested for loops
977.	Squares of a Sorted Array	Python	Easy
980.	Unique Paths III	Python	Hard	"googled soln", optimised
981.	Time Based Key-Value Store	Python	Medium	Binary Search
983.	Minimum Cost For Tickets	Python	Medium	Googled soln
987.	Vertical Order Traversal of a Binary Tree	Python	Medium	DFS
989.	Add to Array-Form of Integer	Python	Easy	list->int->list
991.	Broken Calculator	Python	Medium	BFS
993.	Cousins in Binary Tree	Python	Easy	BFS, iteratively
994.	Rotting Oranges	Python	Medium	DFS
999.	Available Captures for Rook	Python	Easy
1002.	Find Common Characters	Python	Easy	Dictionary
1009.	Complement of Base 10 Integer	Python	Easy
1010.	Pairs of Songs With Total Durations Divisible by 60	Python	Medium
1015.	Smallest Integer Divisible by K	Python	Medium	counting lenght, Brute Force
1019.	Next Greater Node In Linked List	Python	Medium
1021.	Remove Outermost Parentheses	Python	Easy	Overcode
1022.	Sum of Root To Leaf Binary Numbers	Python	Easy	DFS, Recursion
1025.	Divisor Game	Python	Easy
1026.	Maximum Difference Between Node and Ancestor	Python	Medium	BFS, iteratively
1032.	Stream of Characters	Python	Hard	Trie
1038.	Binary Search Tree to Greater Sum Tree	Python	Medium	DFS, recursion
1041.	Robot Bounded In Circle	Python	Medium	Dictionary
1046.	Last Stone Weight	Python	Easy
1047.	Remove All Adjacent Duplicates In String	Python	Easy	Brute force - resolve
1079.	Letter Tile Possibilities	Python	Medium	itertools, permutations
1091.	Shortest Path in Binary Matrix	Python	Medium	BFS, grid/matrix
1094.	Car Pooling	Python	Medium
1095.	Find in Mountain Array	Python	Hard	Binary Search
1103.	Distribute Candies to People	Python	Easy
1108.	Defanging an IP Address	Python	Easy	.replace()
1108.	Defanging an IP Address	Python	Easy	re.sub
1108.	Defanging an IP Address	Python	Easy	.join()
1122.	Relative Sort Array	Python	Easy
1123.	Lowest Common Ancestor of Deepest Leaves	Python	Medium	DFS, recursion
1143.	Longest Common Subsequence	Python	Medium	2D Array
1143.	Longest Common Subsequence	Python	Medium	Recursion, Time Limit Exceeded
1160.	Find Words That Can Be Formed by Characters	Python	Easy	Dictionary
1161.	Maximum Level Sum of a Binary Tree	Python	Medium	BFS
1169.	Invalid Transactions	Python	Medium	Ugly brute force
1171.	Remove Zero Sum Consecutive Nodes from Linked List	Python	Medium	Brute Force - resolve
1189.	Maximum Number of Balloons	Python	Easy	simple counter
1200.	Minimum Absolute Difference	Python	Easy	Dictionary
1207.	Unique Number of Occurrences	Python	Easy	Dictionary
1217.	Minimum Cost to Move Chips to The Same Position	Python	Easy	simple counter
1221.	Split a String in Balanced Strings	Python	Easy	Stack
1227.	Airplane Seat Assignment Probability	Python	Medium
1237.	Find Positive Integer Solution for a Given Equation	Python	Easy	Binary Search
1252.	Cells with Odd Values in a Matrix	Python	Easy
1260.	Shift 2D Grid	Python	Easy	array
1261.	Find Elements in a Contaminated Binary Tree	Python	Medium	DFS, iteratively
1266.	Minimum Time Visiting All Points	Python	Easy	simple counter
1268.	Search Suggestions System	Python	Medium	Brute Force
1282.	Group the People Given the Group Size They Belong To	Python	Medium
1283.	Find the Smallest Divisor Given a Threshold	Python	Medium	Binary Search
1286.	Iterator for Combination	Python	Medium	Itertools
1287.	Element Appearing More Than 25% In Sorted Array	Python	Easy	for loop
1287.	Element Appearing More Than 25% In Sorted Array	Python	Easy	Binary Search
1288.	Remove Covered Intervals	Python	Medium	Brute force
1290.	Convert Binary Number in a Linked List to Integer	Python	Easy
1291.	Sequential Digits	Python	Medium	String, can be solved with int
1299.	Replace Elements with Greatest Element on Right Side	Python	Easy
1302.	Deepest Leaves Sum	Python	Medium	DFS
1304.	Find N Unique Integers Sum up to Zero	Python	Easy
1305.	All Elements in Two Binary Search Trees	Python	Medium	BFS, iteratively
1306.	Jump Game III	Python	Medium	BFS, iteratively
1309.	Decrypt String from Alphabet to Integer Mapping	Python	Easy
1311.	Get Watched Videos by Your Friends	Python	Medium	BFS, iteratively
1313.	Decompress Run-Length Encoded List	Python	Easy
1315.	Sum of Nodes with Even-Valued Grandparent	Python	Medium	DFS, recursion
1323.	Maximum 69 Number	Python	Easy
1325.	Delete Leaves With a Given Value	Python	Medium	DFS, recursion
1329.	Sort the Matrix Diagonally	Python	Medium	List
1331.	Rank Transform of an Array	Python	Easy	Enumerate
1332.	Remove Palindromic Subsequences	Python	Easy	Bad problem question
1337.	The K Weakest Rows in a Matrix	Python	Easy
1338.	Reduce Array Size to The Half	Python	Medium	Dictionary, Enumerate
1342.	Number of Steps to Reduce a Number to Zero	Python	Easy	while loop
1345.	Jump Game IV	Python	Hard	BFS, iteratively
1347.	Minimum Number of Steps to Make Two Strings Anagram	Python	Medium
1348.	Tweet Counts Per Frequency	Python	Medium	Too slow, need to resolve it
1351.	Count Negative Numbers in a Sorted Matrix	Python	Easy	Binary Search
1351.	Count Negative Numbers in a Sorted Matrix	Python	Easy	nested for loop
1351.	Count Negative Numbers in a Sorted Matrix	Python	Easy	nested for loop with a break
1352.	Product of the Last K Numbers	Python	Medium	Brute Force
1352.	Product of the Last K Numbers	Python	Medium	Optimized, but overcode
1352.	Product of the Last K Numbers	Python	Medium
1357.	Apply Discount Every n Orders	Python	Medium	Brute Force
1357.	Apply Discount Every n Orders	Python	Medium	Dictionary
1361.	Validate Binary Tree Nodes	Python	Medium	BFS, iteratively
1365.	How Many Numbers Are Smaller Than the Current Number	Python	Easy	List comprehension
1367.	Linked List in Binary Tree	Python	Medium	DFS, Linked List, Binary Tree
1370.	Increasing Decreasing String	Python	Easy
1374.	Generate a String With Characters That Have Odd Counts	Python	Easy
1379.	Find a Corresponding Node of a Binary Tree in a Clone of That Tree	Python	Medium	Stack, iteratively
1379.	Find a Corresponding Node of a Binary Tree in a Clone of That Tree	Python	Medium	DFS, recursion
1380.	Lucky Numbers in a Matrix	Python	Easy	Nested for loops
1381.	Design a Stack With Increment Operation	Python	Medium	List as Stack
1387.	Sort Integers by The Power Value	Python	Medium
1389.	Create Target Array in the Given Order	Python	Easy	enumerate, insert
1395.	Count Number of Teams	Python	Medium	Brute Force
1396.	Design Underground System	Python	Medium	Dictionary
1403.	Minimum Subsequence in Non-Increasing Order	Python	Easy	List
1403.	Minimum Subsequence in Non-Increasing Order	Python	Easy	sum (int) comparison
1409.	Queries on a Permutation With Key	Python	Medium
1410.	HTML Entity Parser	Python	Medium	Re.sub
1414.	Find the Minimum Number of Fibonacci Numbers Whose Sum Is K	Python	Medium	Greedy
1423.	Maximum Points You Can Obtain from Cards	Python	Medium	Sliding Window
1426.	Counting Elements	Python	Easy
1427.	Perform String Shifts	Python	Easy
1428.	Leftmost Column with at Least a One	Python	Medium
1429.	First Unique Number	Python	Medium
1430.	Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree	Python	Medium
1431.	Kids With the Greatest Number of Candies	Python	Easy	List comprehension
1436.	Destination City	Python	Easy	Dictionary
1436.	Destination City	Python	Easy	Set
1437.	Check If All 1's Are at Least Length K Places Away	Python	Medium
1441.	Build an Array With Stack Operations	Python	Easy	List
1446.	Consecutive Characters	Python	Easy	Two pointers
1448.	Count Good Nodes in Binary Tree	Python	Medium	DFS, Binary Tree
1448.	Count Good Nodes in Binary Tree	Python	Medium	optimized DFS, Binary Tree
1450.	Number of Students Doing Homework at a Given Time	Python	Easy	Enumerate
1455.	Check If a Word Occurs As a Prefix of Any Word in a Sentence	Python	Easy	Enumerate
1457.	Pseudo-Palindromic Paths in a Binary Tree	Python	Medium	DFS, recursion
1460.	Make Two Arrays Equal by Reversing Sub-arrays	Python	Easy
1461.	Check If a String Contains All Binary Codes of Size K	Python	Medium	Brute Force
1463.	Cherry Pickup II	Python	Hard	DFS, lfu cache
1464.	Maximum Product of Two Elements in an Array	Python	Easy
1465.	Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts	Python	Medium
1470.	Shuffle the Array	Python	Easy	Zip
1472.	Design Browser History	Python	Medium	Doubly Linked List
1472.	Design Browser History	Python	Medium	Dictionary
1475.	Final Prices With a Special Discount in a Shop	Python	Easy	kinda Brute force
1476.	Subrectangle Queries	Python	Medium	nested for loop
1480.	Running Sum of 1d Array	Python	Easy
1480.	Running Sum of 1d Array	Python	Easy	List comprehension
1486.	XOR Operation in an Array	Python	Easy
1487.	Making File Names Unique	Python	Medium
1491.	Average Salary Excluding the Minimum and Maximum Salary	Python	Easy
1492.	The kth Factor of n	Python	Medium
1496.	Path Crossing	Python	Easy
1502.	Can Make Arithmetic Progression From Sequence	Python	Easy
1507.	Reformat Date	Python	Easy	List
1507.	Reformat Date	Python	Easy	Without conberting String into List
1512.	Number of Good Pairs	Python	Easy	Dictionary
1512.	Number of Good Pairs	Python	Easy	Nested for loops
1518.	Water Bottles	Python	Easy	While loop
1523.	Count Odd Numbers in an Interval Range	Python	Easy
1528.	Shuffle String	Python	Easy	List
1528.	Shuffle String	Python	Easy	String
1534.	Count Good Triplets	Python	Easy
1539.	Kth Missing Positive Number	Python	Easy	List
1544.	Make The String Great	Python	Easy	Stack
1544.	Make The String Great	Python	Easy	String in-place
1545.	Find Kth Bit in Nth Binary String	Python	Medium	Brute Force
1550.	Three Consecutive Odds	Python	Easy	simple counter
1551.	Minimum Operations to Make Array Equal	Python	Medium
1556.	Thousand Separator	Python	Easy	String, List
1557.	Minimum Number of Vertices to Reach All Nodes	Python	Medium	Set, kinda Brute Force
1561.	Maximum Number of Coins You Can Get	Python	Medium
1566.	Detect Pattern of Length M Repeated K or More Times	Python	Easy
1567.	Maximum Length of Subarray With Positive Product	Python	Medium	kinda Brute force
1572.	Matrix Diagonal Sum	Python	Easy
1576.	Replace All ?'s to Avoid Consecutive Repeating Characters	Python	Easy	Fast but awful soln.
1582.	Special Positions in a Binary Matrix	Python	Easy
1588.	Sum of All Odd Length Subarrays	Python	Easy	Two Pointers
1592.	Rearrange Spaces Between Words	Python	Easy
1598.	Crawler Log Folder	Python	Easy
1603.	Design Parking System	Python	Easy	Dictionary
1609.	Even Odd Tree	Python	Medium	BFS
1614.	Maximum Nesting Depth of the Parentheses	Python	Easy
1619.	Mean of Array After Removing Some Elements	Python	Easy
1624.	Largest Substring Between Two Equal Characters	Python	Easy
1629.	Slowest Key	Python	Easy
1630.	Arithmetic Subarrays	Python	Medium
1631.	Path With Minimum Effort	Python	Medium	DFS, Binary Search, Brute force
1636.	Sort Array by Increasing Frequency	Python	Easy	complicated counter
1637.	Widest Vertical Area Between Two Points Containing No Points	Python	Medium
1640.	Check Array Formation Through Concatenation	Python	Easy
1641.	Count Sorted Vowel Strings	Python	Medium	itertools
1646.	Get Maximum in Generated Array	Python	Easy	while
1646.	Get Maximum in Generated Array	Python	Easy	for
1652.	Defuse the Bomb	Python	Easy
1656.	Design an Ordered Stream	Python	Easy	list
1657.	Determine if Two Strings Are Close	Python	Medium	collections.Counter
1658.	Minimum Operations to Reduce X to Zero	Python	Medium
1662.	Check If Two String Arrays are Equivalent	Python	Easy	.join()
1663.	Smallest String With A Given Numeric Value	Python	Medium
1668.	Maximum Repeating Substring	Python	Easy
1669.	Merge In Between Linked Lists	Python	Medium	Linked List
1670.	Design Front Middle Back Queue	Python	Medium	List
1672.	Richest Customer Wealth	Python	Easy
1673.	Find the Most Competitive Subsequence	Python	Medium	Stack
1678.	Goal Parser Interpretation	Python	Easy	.replace()
1678.	Goal Parser Interpretation	Python	Easy	iteratively
1679.	Max Number of K-Sum Pairs	Python	Medium	collections, Counter
1680.	Concatenation of Consecutive Binary Numbers	Python	Medium
1684.	Count the Number of Consistent Strings	Python	Easy
1685.	Sum of Absolute Differences in a Sorted Array	Python	Medium
1688.	Count of Matches in Tournament	Python	Easy	simple counter
1689.	Partitioning Into Minimum Number Of Deci-Binary Numbers	Python	Medium	max()
1694.	Reformat Phone Number	Python	Easy
1695.	Maximum Erasure Value	Python	Medium
1700.	Number of Students Unable to Eat Lunch	Python	Easy	simple counter
1704.	Determine if String Halves Are Alike	Python	Easy	simple counter
1710.	Maximum Units on a Truck	Python	Easy	Dictionary
1716.	Calculate Money in Leetcode Bank	Python	Easy
1720.	Decode XORed Array	Python	Easy
1721.	Swapping Nodes in a Linked List	Python	Medium	Linked List, Queue
1725.	Number Of Rectangles That Can Form The Largest Square	Python	Easy	collections.defaultdict
1732.	Find the Highest Altitude	Python	Easy
1748.	Sum of Unique Elements	Python	Easy	collections.Counter
1752.	Check if Array Is Sorted and Rotated	Python	Easy
1773.	Count Items Matching a Rule	Python	Easy
1790.	Check if One String Swap Can Make Strings Equal	Python	Easy
1791.	Find Center of Star Graph	Python	Medium
1796.	Second Largest Digit in a String	Python	Easy
1800.	Maximum Ascending Subarray Sum	Python	Easy
1805.	Number of Different Integers in a String	Python	Easy
1812.	Determine Color of a Chessboard Square	Python	Easy
1816.	Truncate Sentence	Python	Easy

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License

The code is open-source and licensed under the MIT license.