LeetCode_Challenge

This Challenge is beginner-friendly and available to both Premium and non-Premium users. It consists of 30-31 daily problems depends on the month type. A problem is added here each day, and you have 24 hours to make a valid submission for it in order to be eligible for rewards.

In this LeetCode Challenge, we challenge participants with a problem from our carefully curated collection of interview problems every 24 hours. All users with all levels of coding background are welcome to join!

📌 When is August's LeetCoding Challenge? Start: August 1st, 12:00 AM in Pacific Time (UTC-7)

End: August 31th, 23:59 PM in Pacific Time (UTC-7)

🚩 How do I join August's LeetCoding Challenge?

To join, just start solving problems in August's LeetCoding Challenge Explore Card. No registration is required. The first problem will appear in the Explore card on August's 1st, 12 a.m. Pacific Time and you will have 24 hours to solve that challenge. A problem is added in the Explore card each day. For more details such as the Challenge Rules, please refer to the Explore card.

🎁 Rewards:

Completing each daily challenge. (+10 LeetCoins)

Completing 25 to 30 daily challenges will be eligible for an additional 100 LeetCoins. (Total = 350 to 400 LeetCoins)

Completing all 31 daily challenges will be eligible for 2X the reward, plus a chance to win a secret prize ( Total = 620 LeetCoins + *Lucky Draw)!

Lucky Draw: Those who complete all 31 daily challenges will be automatically entered into a Lucky Draw, where LeetCode staff will randomly select 3 lucky participants to each receive one LeetCode Cap on top of their rewards!

🤩 What are you waiting for? Mark your calendar now to start the August LeetCoding Challenge on August 1st, 2022!

LeetCode Algorithms

Problems

May-2022

#	Title	Solution	Tags	Youtube
1	Backspace String Compare		two pointers string stack simulation
2	Sort Array By Parity		array two pointers string
3	Shortest Unsorted Continuous Subarray		array two pointers stack greedy sorting monotonic stack
4	Max Number of K-Sum Pairs		array hash table two pointers sorting
5	Implement Stack using Queues		stack design queue
6	Remove All Adjacent Duplicates in String II		string stack
7	132 Pattern		array binary search stack monotonic stack ordered set
8	Flatten Nested List Iterator		stack tree depth-first search design queue iterator
9	Letter Combinations of a Phone Number		hash table string backtracking
10	Combination Sum III		array backtracking
11	Count Sorted Vowel Strings		dynamic programming
12	Permutations II		array backtracking
13	Populating Next Right Pointers in Each Node II		linked list tree depth-first search breadth-first search binary tree
14	Network Delay Time		depth-first search breadth-first search graph heap(priority queue) shortest path
15	Deepest Leaves Sum		tree depth-first search breadth-first search binary tree
16	Shortest Path in Binary Matrix		array breadth-first search matrix
17	Find a Corresponding Node of a Binary Tree in a Clone of That Tree		tree depth-first search breadth-first search binary tree
18	Critical Connections in a Network		depth-first search graph biconnected component
19	Longest Increasing Path in a Matrix		dynamic programming depth-first search breadth-first search graph topological sort memorization
20	Unique Paths II		array dynamic programming matrix
21	Coin Change		array dynamic programming breadth-first search
22	Palindromic Substrings		string dynamic programming
23	Ones and Zeroes		array string dynamic programming
24	Longest Valid Parentheses		string dynamic programming stack
25	Russian Doll Envelopes		array binary search dynamic programming sorting
26	Number of 1 Bits		divide and conquer bit manipulation
27	Number of Steps to Reduce a Number to Zero		math bit manipulation
28	Missing Number		array hash table math binary search bit manipulation sorting
29	Maximum Product of Word Lengths		array string bit manipulation
30	Divide Two Integers		math bit manipulation
31	Check If a String Contains All Binary Codes of Size K		hash table string bit manipulation rolling hash hash function

June-2022

#	Title	Solution	Tags	Youtube
1	Running Sum of 1D Array		array prefix sum
2	Transpose Matrix		array matrix simulation
3	Range Sum Query 2D - Immutable		array
4	N-Queens		array backtracking
5	N-Queens-II		backtracking
6	Intersection of Two Linked Lists		hash table linked list two pointers
7	Merge Sorted Array		array two pointers sorting
8	Remove Palindromic Subsequences		two pointers string
9	Two Sum II - Input Array Is Sorted		array two pointers binary search
10	Longest Substring Without Repeating Characters		hash table string sliding window
11	Minimum Operations to Reduce X to Zero		array hash table binary search sliding window prefix sum
12	Maximum Erasure Value		array hash table sliding window
13	Triangle		array dynamic programming
14	Delete Operation for Two Strings		string dynamic programming
15	Longest String Chain		array hash table two pointers string dynamic programming
16	Longest Palindromic Substring		string dynamic programming
17	Binary Tree Cameras		dynamic programming tree depth-first search binary tree
18	Prefix and Suffix Search		string design trie
19	Search Suggestions System		array string trie
20	Short Encoding of Words		array hash table string trie
21	Furthest Building You Can Reach		array greedy heap(priority queue)
22	Kth Largest Element in an Array		array divide and conquer sorting heap(priority queue) quickselect
23	Course Schedule III		array greedy heap(priority queue)
24	Construct Target Array With Multiple Sums		array heap(priority queue)
25	Non-decreasing Array		array
26	Maximum Points You Can Obtain from Cards		array sliding window prefix sum
27	Partitioning Into Minimum Number Of Deci-Binary Numbers		string greedy
28	Minimum Deletions to Make Character Frequencies Unique		string greedy sorting
29	Queue Reconstruction by Height		array greedy binary indexed tree segment tree sorting
30	Minimum Moves to Equal Array Elements II		string

July-2022

#	Title	Solution	Tags	Youtube
1	Maximum Units on a Truck		array greedy sorting
2	Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts		array greedy sorting
3	Wiggle Subsequence		array dynamic programming greedy
4	Candy		array greedy
5	Longest Consecutive Sequence		array hash table union find
6	Fibonacci Number		math dynamic programming recursion memoization
7	Interleaving String		string dynamic programming
8	Paint House III		array dynamic programming
9	Jump Game VI		array dynamic programming queue sliding window heap(priority queue) monotonic queue
10	Min Cost Climbing Stairs		array dynamic programming
11	Binary Tree Right Side View		trees depth-first search breadth-first search binary tree
12	Matchsticks to Square		array dynamic programming backtracking bit manipulation bitmask
13	Binary Tree Level Order Traversal		tree breadth-first search binary tree
14	Construct Binary Tree from Preorder and Inorder Traversal		array hash table divide and conquer tree binary tree
15	Max Area of Island		array depth-first search breadth-first search union find matrix
16	Out of Boundary Paths		dynamic programming
17	K Inverse Pairs Array		dynamic programming
18	Number of Submatrices That Sum to Target		array hash table matrix prefix sum
19	Pascal's Triangle		array dynamic programming
20	Number of Matching Subsequences		hash table string trie sorting
21	Reverse Linked List II		Linked List
22	Partition List		Linked List Two Pointers
23	Count of Smaller Numbers After Self		array binary search divide and conquer binary indexed tree segment tree merge sort ordered set
24	Search a 2D Matrix II		array binary search divide and conquer matrix
25	Find First and Last Position of Element in Sorted Array		array binary search
26	Lowest Common Ancestor of a Binary Tree		tree depth-first search binary tree
27	Flatten Binary Tree to Linked List		linked list stack tree depth-first search binary tree
28	Valid Anagram		hash table string sorting
29	Find and Replace Pattern		array hash table string
30	Word Subsets		array hash table string
31	Range Sum Query - Mutable		array design binary indexed tree segment tree

August-2022

#	Title	Solution	Tags	Youtube
1	Unique Paths		math dynamic programming combinatorics
2	Kth Smallest Element in a Sorted Matrix		array binary search sorting heap(priority queue) matrix
3	My Calendar I		binary search design segment tree ordered set
4	Mirror Reflection		math geometry
5	Combination Sum IV		array dynamic programming
6	Poor Pigs		math dynamic programming combinatorics
7	Count Vowels Permutation		dynamic programming
8	Longest Increasing Subsequence		array binary search dynamic programming
9	Binary Trees With Factors		array hash table dynamic programming
10	Convert Sorted Array to Binary Search Tree		array divide and conquer tree binary search tree binary search
11	Validate Binary Search Tree		tree depth-first search binary search tree bianry tree
12	Lowest Common Ancestor of a Binary Search Tree		tree depth-first search binary search tree bianry tree
13	Substring with Concatenation of All Words		hash table string sliding window
14	Word Ladder II		hash table string backtracking breadth-first search
15	Roman to Integer		hash table math string
16	First Unique Character in a String		hash table string queue counting
17	Unique Morse Code Words		array hash table string
18	Reduce Array Size to The Half		array hash table greedy sorting heap(priority queue)
19	Split Array into Consecutive Subsequences		array hash table greedy heap(priority queue)
20	Minimum Number of Refueling Stops		array dynamic programming greedy heap(priority queue)
21	Stamping The Sequence		string stack greedy queue
22	Power of Four		math bit manipulation recursion
23	Palindrome Linked List		linked list two pointers stack recursion
24	Power of Three		math recursion
25	Ransom Note		hash table string counting
26	Reordered Power of 2		math string counting enumeration
27	Max Sum of Rectangle No Larger Than K		array binary search matrix prefix sum ordered set
28	Sort the Matrix Diagonally		array sorting matrix
29	Number of Islands		array depth-first search breadth-first search union find matrix
30	Rotate Image		array math matrix
31	Pacific Atlantic Water Flow		array depth-first search breadth-first search matrix