Track of Daily Challenges

Year	Jan	Feb	March	April	May	June	July	Aug	Sept	Oct	Nov	Dec
2020						12/30	26/31	20/31	30/30	31/31	29/30	27/31
2021	25/31	28/28	31/31	20/31

June, 2020 Challenge

Date	problem-link	solution
01/06/2020	Invert Binary Tree	solution
02/06/2020	Delete Node in a Linked List	solution
03/06/2020		solution
04/06/2020	Reverse String	solution
05/06/2020		solution
06/06/2020		solution
07/06/2020	Coin Change 2	solution
08/06/2020	Power of Two	solution
09/06/2020	Is Subsequence	solution
10/06/2020	Search Insert Position	solution
11/06/2020	Sort Colors	solution
12/06/2020		solution
13/06/2020		solution
14/06/2020		solution
15/06/2020	Search in a Binary Search Tree	solution
16/06/2020	Validate IP Address	solution
17/06/2020	Surrounded Regions	solution
18/06/2020	H-Index II	solution
19/06/2020		solution
20/06/2020		solution
21/06/2020		solution
22/06/2020		solution
23/06/2020		solution
24/06/2020		solution
25/06/2020		solution
26/06/2020		solution
27/06/2020		solution
28/06/2020		solution
29/06/2020		solution
30/06/2020		solution

July, 2020 Challenge

Date	problem-link	solution
01/06/2020	Arranging Coins	solution
02/06/2020	Binary Tree Level Order Traversal II	solution
03/06/2020	Prison Cells After N Days	solution
04/06/2020	Ugly Number II	solution
05/06/2020	Hamming Distance	solution
06/06/2020	Plus One	solution
07/06/2020	Island Perimeter	solution
08/06/2020	3Sum	solution
09/06/2020	Maximum Width of Binary Tree	solution
10/06/2020	Flatten a Multilevel Doubly Linked List	solution
11/06/2020	Subsets	solution
12/06/2020	Reverse Bits	solution
13/06/2020	Same Tree	solution
14/06/2020	Angle Between Hands of a Clock	solution
15/06/2020	Reverse Words in a String	solution
16/06/2020	Pow(x, n)	solution
17/06/2020	Top K Frequent Elements	solution
18/06/2020	Course Schedule II	solution
19/06/2020	Add Binary	solution
20/06/2020	Remove Linked List Elements	solution
21/06/2020		solution
22/06/2020	Binary Tree Zigzag Level Order Traversal	solution
23/06/2020	Single Number III	solution
24/06/2020		solution
25/06/2020	Find Minimum in Rotated Sorted Array II	solution
26/06/2020	Add Digits	solution
27/06/2020		solution
28/06/2020	Task Scheduler	solution
29/06/2020		solution
30/06/2020		solution
31/06/2020	Climbing Stairs	solution

August, 2020 Challenge

Date	problem-link	solution
01/08/2020	Detect Capital	solution
02/08/2020	Design HashSet	solution
03/08/2020	Valid Palindrome	solution
04/08/2020	Power of Four	solution
05/08/2020	Add and Search Word - Data structure design	solution
06/08/2020	Find All Duplicates in an Array	solution
07/08/2020	Vertical Order Traversal of a Binary Tree	solution
08/08/2020		solution
09/08/2020		solution
10/08/2020	Excel Sheet Column Number	solution
11/08/2020	H-Index	solution
12/08/2020	Pascal's Triangle II	solution
13/08/2020	Iterator for Combination	solution
14/08/2020	Longest Palindrome	solution
15/08/2020	Non-overlapping Intervals	solution
16/08/2020	Best Time to Buy and Sell Stock III	solution
17/08/2020	Distribute Candies to People	solution
18/08/2020	Numbers With Same Consecutive Differences	solution
19/08/2020	Goat Latin	solution
20/08/2020	Reorder List	solution
21/08/2020	Sort Array By Parity	solution
22/08/2020		solution
23/08/2020		solution
24/08/2020		solution
25/08/2020		solution
26/08/2020	Fizz Buzz	solution
27/08/2020		solution
28/08/2020		solution
29/08/2020		solution
30/08/2020		solution
31/08/2020	Delete Node in a BST	solution

September, 2020 Challenge

Date	problem-link	solution
01/09/2020	Largest Time for Given Digits	solution
02/09/2020	Contains Duplicate III	solution
03/09/2020	Repeated Substring Pattern	solution
04/09/2020	Partition Labels	solution
05/09/2020	All Elements in Two Binary Search Trees	solution
06/09/2020	Image Overlap	solution
07/09/2020	Word Pattern	solution
08/09/2020	Sum of Root To Leaf Binary Numbers	solution
09/09/2020	Compare Version Numbers	solution
10/09/2020	Bulls and Cows	solution
11/09/2020	Maximum Product Subarray	solution
12/09/2020	Combination Sum III	solution
13/09/2020	Insert Interval	solution
14/09/2020	House Robber	solution
15/09/2020	Length of Last Word	solution
16/09/2020	Maximum XOR of Two Numbers in an Array	solution
17/09/2020	Robot Bounded In Circle	solution
18/09/2020	Best Time to Buy and Sell Stock	solution
19/09/2020	Sequential Digits	solution
20/09/2020	Unique Paths III	solution
21/09/2020	Car Pooling	solution
22/09/2020	Majority Element II	solution
23/09/2020	Gas Station	solution
24/09/2020	Find the Difference	solution
25/09/2020	Largest Number	solution
26/09/2020	Teemo Attacking	solution
27/09/2020	Evaluate Divison	solution
28/09/2020	Subarray Product Less Than K	solution
29/09/2020	Word Break	solution
30/09/2020	First Missing Positive	solution

October, 2020 Challenge

Date	problem-link	solution
01/10/2020	Number of Recent Calls	solution
02/10/2020	Combination Sum	solution
03/10/2020	K-diff Pairs in an Array	solution
04/10/2020	Remove Covered Intervals	solution
05/10/2020	Complement of Base 10 Integer	solution
06/10/2020	Insert into a Binary Search Tree	solution
07/10/2020	Rotate List	solution
08/10/2020	Binary Search	solution
09/10/2020	Serialize and Deserialize BST	solution
10/10/2020	Minimum Number of Arrows to Burst Balloons	solution
11/10/2020	Remove Duplicate Letters	solution
12/10/2020	Buddy Strings	solution
13/10/2020	Sort List	solution
14/10/2020	House Robber II	solution
15/10/2020	Rotate Array	solution
16/10/2020	Search a 2D Matrix	solution
17/10/2020	Repeated DNA Sequences	solution
18/10/2020	Best Time to Buy and Sell Stock IV	solution
19/10/2020	Minimum Domino Rotations For Equal Row	solution
20/10/2020	Clone Graph	solution
21/10/2020	Asteroid Collision	solution
22/10/2020	Minimum Depth of Binary Tree	solution
23/10/2020	132 Pattern	solution
24/10/2020	Bag of Tokens	solution
25/10/2020	Stone Game IV	solution
26/10/2020	Champagne Tower	solution
27/10/2020	Linked List Cycle II	solution
28/10/2020	Summary Ranges	solution
29/10/2020	Maximize Distance to Closest Person	solution
30/10/2020	Number of Longest Increasing Subsequence	solution
31/10/2020	Recover Binary Search Tree	solution

November, 2020 Challenge

Date	problem-link	solution
01/11/2020	Convert Binary Number in a Linked List to Integer	solution
02/11/2020	Insertion Sort List	solution
03/11/2020	Consecutive Characters	solution
04/11/2020	Minimum Height Trees	solution
05/11/2020	Minimum Cost to Move Chips to The Same Position	solution
06/11/2020	Find the Smallest Divisor Given a Threshold	solution
07/11/2020	Add Two Numbers II	solution
08/11/2020	Binary Tree Tilt	solution
09/11/2020	Maximum Difference Between Node and Ancestor	solution
10/11/2020	Flipping an Image	solution
11/11/2020	Valid Square	solution
12/11/2020	Permutations II	solution
13/11/2020	Populating Next Right Pointers in Each Node	solution
14/11/2020	Poor Pigs	solution
15/11/2020	Range Sum of BST	solution
16/11/2020	Longest Mountain in Array	solution
17/11/2020	Mirror Reflection	solution
18/11/2020	Merge Intervals	solution
19/11/2020	Decode String	solution
20/11/2020	Search in Rotated Sorted Array II	solution
21/11/2020	Numbers At Most N Given Digit Set	solution
22/11/2020	Unique Morse Code Words	solution
23/11/2020	House Robber III	solution
24/11/2020	Basic Calculator II	solution
25/11/2020	Smallest Integer Divisible by K	solution
26/11/2020	Longest Substring with At Least K Repeating Characters	solution
27/11/2020	Partition Equal Subset Sum	solution
28/11/2020	Sliding Window Maximum	solution
29/11/2020	Jump Game III	solution
30/11/2020		solution

December, 2020 Challenge

Date	problem-link	solution
01/12/2020	Maximum Depth of Binary Tree	solution
02/12/2020	Linked List Random Node	solution
03/12/2020	Increasing Order Search Tree	solution
04/12/2020	The kth Factor of n	solution
05/12/2020	Can Place Flowers	solution
06/12/2020	Populating Next Right Pointers in Each Node II.py	solution
07/12/2020	Spiral Matrix II	solution
08/12/2020	Pairs of Songs With Total Durations Divisible by 60	solution
09/12/2020	Binary Search Tree Iterator	solution
10/12/2020	Valid Mountain Array	solution
11/12/2020	Remove Duplicates from Sorted Array II	solution
12/12/2020	Smallest Subtree with all the Deepest Nodes	solution
13/12/2020	Burst Balloons	solution
14/12/2020		solution
15/12/2020	Squares of a Sorted Array	solution
16/12/2020	Validate Binary Search Tree	solution
17/12/2020	4Sum II	solution
18/12/2020	Increasing Triplet Subsequence	solution
19/12/2020		solution
20/12/2020		solution
21/12/2020	Decoded String at Index	solution
22/12/2020	Balanced Binary Tree	solution
23/12/2020	Next Greater Element III	solution
24/12/2020	Swap Nodes in Pairs	solution
25/12/2020	Diagonal Traverse	solution
26/12/2020	Decode Ways	solution
27/12/2020	Jump Game IV	solution
28/12/2020	Reach a Number	solution
29/12/2020		solution
30/12/2020	Game of Life	solution
31/12/2020	Largest Rectangle in Histogram	solution

January, 2021 Challenge

Date	problem-link	solution
01/01/2021	Check Array Formation Through Concatenation	solution
02/01/2021	Find a Corresponding Node of a Binary Tree in a Clone of That Tree	solution
03/01/2021	Beautiful Arrangement	solution
04/01/2021	Merge Two Sorted Lists	solution
05/01/2021	Remove Duplicates from Sorted List II	solution
06/01/2021	Kth Missing Positive Number	solution
07/01/2021	Longest Substring Without Repeating Characters	solution
08/01/2021	Check If Two String Arrays are Equivalent	solution
09/01/2021	Word Ladder	solution
10/01/2021	Create Sorted Array through Instructions	solution
11/01/2021	Merge Sorted Array	solution
12/01/2021	Add Two Numbers	solution
13/01/2021	Boats to Save People	solution
14/01/2021	Minimum Operations to Reduce X to Zero	solution
15/01/2021	Get Maximum in Generated Array	solution
16/01/2021	Kth Largest Element in an Array	solution
17/01/2021	Count Sorted Vowel Strings	solution
18/01/2021	Max Number of K-Sum Pairs	solution
19/01/2021	Longest Palindromic Substring	solution
20/01/2021	Valid Parentheses	solution
21/01/2021	Find the Most Competitive Subsequence	solution
22/01/2021	Determine if Two Strings Are Close	solution
23/01/2021	Sort the Matrix Diagonally	solution
24/01/2021	Merge k Sorted Lists	solution
25/01/2021		solution
26/01/2021		solution
27/01/2021		solution
28/01/2021		solution
29/01/2021	Vertical Order Traversal of a Binary Tree	solution
30/01/2021		solution
31/01/2021		solution

February, 2021 Challenge

Date	problem-link	solution
01/02/2021	Number of 1 Bits	solution
02/02/2021	Trim a Binary Search Tree	solution
03/02/2021	Linked List Cycle	solution
04/02/2021	Longest Harmonious Subsequence	solution
05/02/2021	Simplify Path	solution
06/02/2021	Binary Tree Right Side View	solution
07/02/2021	Shortest Distance to a Character	solution
08/02/2021	Peeking Iterator	solution
09/02/2021	Convert BST to Greater Tree	solution
10/02/2021	Copy List with Random Pointer	solution
11/02/2021	Valid Anagram	solution
12/02/2021	Number of Steps to Reduce a Number to Zero	solution
13/02/2021	Shortest Path in Binary Matrix	solution
14/02/2021	Is Graph Bipartite?	solution
15/02/2021	The K Weakest Rows in a Matrix	solution
16/02/2021	Letter Case Permutation	solution
17/02/2021	Container With Most Water	solution
18/02/2021	Arithmetic Slices	solution
19/02/2021	Minimum Remove to Make Valid Parentheses	solution
20/02/2021	Roman to Integer	solution
21/02/2021	Broken Calculator	solution
22/02/2021	Longest Word in Dictionary through Deleting	solution
23/02/2021	Search a 2D Matrix II	solution
24/02/2021	Score of Parentheses	solution
25/02/2021	Shortest Unsorted Continuous Subarray	solution
26/02/2021	Validate Stack Sequences	solution
27/02/2021	Divide Two Integers	solution
28/02/2021	Maximum Frequency Stack	solution

March, 2021 Challenge

Date	problem-link	solution
01/03/2021	Distribute Candies	solution
02/03/2021	Set Mismatch	solution
03/03/2021	Missing Number	solution
04/03/2021	Intersection of Two Linked Lists	solution
05/03/2021	Average of Levels in Binary Tree	solution
06/03/2021	Short Encoding of Words	solution
07/03/2021	Design HashMap	solution
08/03/2021	Remove Palindromic Subsequences	solution
09/03/2021	Add One Row to Tree	solution
10/03/2021	Integer to Roman	solution
11/03/2021	Coin Change	solution
12/03/2021	Check If a String Contains All Binary Codes of Size K	solution
13/03/2021	Binary Trees With Factors	solution
14/03/2021	Swapping Nodes in a Linked List	solution
15/03/2021	Encode and Decode TinyURL	solution
16/03/2021	Best Time to Buy and Sell Stock with Transaction Fee	solution
17/03/2021	Generate Random Point in a Circle	solution
18/03/2021	Wiggle Subsequence	solution
19/03/2021	Keys and Rooms	solution
20/03/2021	Design Underground System	solution
21/03/2021	Reordered Power of 2	solution
22/03/2021	Vowel Spellchecker	solution
23/03/2021	3Sum With Multiplicity	solution
24/03/2021	Advantage Shuffle	solution
25/03/2021	Pacific Atlantic Water Flow	solution
26/03/2021	Word Subsets	solution
27/03/2021	Palindromic Substrings	solution
28/03/2021	Reconstruct Original Digits from English	solution
29/03/2021	Flip Binary Tree To Match Preorder Traversal	solution
30/03/2021	Russian Doll Envelopes	solution
31/03/2021	Stamping The Sequence	solution

April, 2021 Challenge

Date	problem-link	solution
01/04/2021	Palindrome Linked List	solution
02/04/2021	Ones and Zeroes	solution
03/04/2021	Longest Valid Parentheses	solution
04/04/2021	Design Circular Queue	solution
05/04/2021	Global and Local Inversions	solution
06/04/2021	Minimum Operations to Make Array Equal	solution
07/04/2021	Determine if String Halves Are Alike	solution
08/04/2021	Letter Combinations of a Phone Number	solution
09/04/2021	Verifying an Alien Dictionary	solution
10/04/2021	Longest Increasing Path in a Matrix	solution
11/04/2021	Deepest Leaves Sum	solution
12/04/2021	Beautiful Arrangement II	solution
13/04/2021	Flatten Nested List Iterator	solution
14/04/2021	Partition List	solution
15/04/2021	Fibonacci Number	solution
16/04/2021	Remove All Adjacent Duplicates in String II	solution
17/04/2021		solution
18/04/2021	Remove Nth Node From End of List	solution
19/04/2021	Combination Sum IV	solution
20/04/2021	N-ary Tree Preorder Traversal	solution
21/04/2021	Triangle	solution
22/04/2021		solution
23/04/2021		solution
24/04/2021		solution
25/04/2021		solution
26/04/2021		solution
27/04/2021	Power of Three	solution
28/04/2021		solution
29/04/2021	Find First and Last Position of Element in Sorted Array	solution
30/04/2021		solution

icon credits

Icons made by Freepik from www.flaticon.com