LeetCode

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November LeetCoding Challenge

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Solutions in various programming languages are provided. Enjoy it.

1. Convert Binary Number in a Linked List to Integer
2. Insertion Sort List
3. Consecutive Characters
4. Minimum Height Trees
5. Minimum Cost to Move Chips to The Same Position
6. Find the Smallest Divisor Given a Threshold
7. Add Two Numbers II
8. Binary Tree Tilt
9. Maximum Difference Between Node and Ancestor
10. Flipping an Image
11. Valid Square
12. Permutations II
13. Populating Next Right Pointers in Each Node
14. Poor Pigs
15. Range Sum of BST
16. Longest Mountain in Array
17. Mirror Reflection
18. Merge Intervals
19. Decode String
20. Search in Rotated Sorted Array II
21. Numbers At Most N Given Digit Set
22. Unique Morse Code Words

October LeetCoding Challenge

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Solutions in various programming languages are provided. Enjoy it.

1. Number of Recent Calls : Queue
2. Combination Sum
3. K-diff Pairs in an Array
4. Remove Covered Intervals
5. Complement of Base 10 Integer
6. Insert into a Binary Search Tree
7. Rotate List
8. Binary Search
9. Serialize and Deserialize BST
10. Minimum Number of Arrows to Burst Balloons
11. Remove Duplicate Letters
12. Buddy Strings
13. Sort List
14. House Robber II
15. Rotate Array
16. Search a 2D Matrix
17. Repeated DNA Sequences
18. Best Time to Buy and Sell Stock IV
19. Minimum Domino Rotations For Equal Row
20. Clone Graph
21. Asteroid Collision
22. Minimum Depth of Binary Tree
23. 132 Pattern
24. Bag of Tokens
25. Stone Game IV
26. Champagne Tower
27. Linked List Cycle II
28. Summary Ranges
29. Maximum Distance to Closest Person
30. Number of Longest Increasing Subsequence
31. Recover Binary Search Tree

September LeetCoding Challenge

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Solutions in various programming languages are provided. Enjoy it.

1. Largest Time for Given Digits
2. Contains Duplicate III
3. Repeated Substring Pattern
4. Partition Labels
5. All Elements in Two Binary Search Trees
6. Image Overlap
7. Word Pattern
8. Sum of Root To Leaf Binary Numbers
9. Compare Version Numbers
10. Bulls and Cows
11. Maximum Product Subarray
12. Combination Sum III
13. Insert Interval
14. House Robber
15. Length of Last Word
16. Maximum XOR of Two Numbers in an Array
17. Robot Bounded In Circle
18. Best Time to Buy and Sell Stock
19. Sequential Digits
20. Gas Station
21. Subarray Product Less Than K
22. First Missing Positive

August LeetCoding Challenge

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Solutions in various programming languages are provided. Enjoy it.

1. Detect Capital
2. Design HashSet
3. Valid Palindrome
4. Power of Four
5. Add and Search Word Data structure design
6. Find All Duplicates in an Array
7. Vertical Order Traversal of a Binary Tree
8. Path Sum III
9. Rotting Oranges
10. Excel Sheet Column Number
11. H-Index
12. Pascal's Triangle II
13. Iterator for Combination
14. Longest Palindrome
15. Non-overlapping Intervals
16. Best Time to Buy and Sell Stock III
17. Distribute Candies to People
18. Numbers With Same Consecutive Differences
19. Goat Latin
20. Reorder List
21. Sort Array By Parity
22. Random Point in Non-overlapping Rectangles
23. Stream of Characters
24. Sum of Left Leaves
25. Minimum Cost For Tickets
26. Fizz Buzz
27. Find Right Interval
28. Implement Rand10() Using Rand7()
29. Pancake Sorting
30. Largest Component Size by Common Factor
31. Delete Node in a BST

July LeetCoding Challenge

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Solutions in various programming languages are provided. Enjoy it.

1. Arranging Coins: Maths
2. Binary Tree Level Order Traversal II: DFS
3. Prison Cells After N Days: Maths
4. Ugly Number II: DP
5. Hamming Distance: Bitwise Manipulation
6. Plus One: Maths
7. Island Perimeter: BFS
8. 3Sum: Two pointers
9. Maximum Width of Binary Tree: DFS
10. Flatten a Multilevel Doubly Linked List: Queue
11. Subsets: DP
12. Reverse Bits: Bitwise
13. Same Tree: DFS
14. Angle Between Hands of a Clock: Math
15. Reverse Words in a String: Pointer
16. Pow(x,n): Recursion
17. Top K Frequent Elements: Bucket
18. Course Schedule II: BFS
19. Add Binary
20. Remove Linked List Elements
21. Word Search
22. Binary Tree Zigzag Level Order Traversal
23. Single Number III
24. All Paths From Source to Target
25. Find Minimum in Rotated Sorted Array II
26. Add Digits
27. Construct Binary Tree from Inorder and Postorder Traversal
28. Task Scheduler
29. Best Time to Buy and Sell Stock with Cooldown: State machine
30. Word Break II
31. Climbing Stairs: DP

June LeetCoding Challenge

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Solutions in various programming languages are provided. Enjoy it.

1. Invert Binary Tree: Tree Traversal
2. Delete Node in a Linked List: Linked List
3. Two City Scheduling: DP
4. Reverse String: String
5. Random Pick With Weight: Binary Search + Probability
6. Queue Reconstruction by Height: Greedy
7. Coin Change 2: DP
8. Power of Two: Bitwise manipulation
9. Is Subsequence: Two pointers / DP
10. Search Insert Position: Binary Search
11. Sort Colors: Two Pointers
12. Insert Delete GetRandom: Hash Table
13. Largest Divisible Subset: DP
14. Cheapest Flights Within K Stops: DP
15. Search in a Binary Search Tree: Recursive
16. Validate IP Address: String
17. Surrounded Regions: BFS
18. H Index II: Binary Search
19. Longest Duplicate Substring:
20. Permutation Sequence: Maths
21. Dungeon Game: DP
22. Single Number II: Bitwise Manipulation
23. Count Complete Tree Nodes: Tree Traversal
24. Unique Binary Search Trees: DP
25. Find the Duplicate Number: Cycle Detect
26. Sum Root To Leaf Numbers: DFS
27. Perfect Squares: DP
28. Reconstruct Itinerary: DFS
29. Unique Paths: DP
30. Word Search: Trie + DFS

May LeetCoding Challenge

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Solutions in various programming languages are provided. Enjoy it.

1. First Bad String: Binary search.
2. Jewels and Stones: Hash Table
3. Ransom Note: Hash Table
4. Number Complement: Bitwise Manipulation
5. First Unique Character In a String: Hash Table
6. Majority Element: Ad hoc
7. Cousins in Binary Tree: BFS / Recursion
8. Check if it is straight line: Cross Product
9. Valid Perfect Square: Math
10. Find the Town Judge: Graph Theory
11. Flood Fill: BFS
12. Single Element In a Sorted Array: Binary Search
13. Remove K Digits: Greedy
14. Implement Trie: Trie
15. Maximum Sum Circular Subarray: DP
16. Odd Even Linked List: Linked List
17. Find All Anagrams in a String: Sliding window + Hash Table
18. Permutation In String: Sliding window + Hash Table
19. Online Stock Span: DP
20. Kth-Smallest-Element-In-A-BST: BST
21. Count Square Submatrices with All Ones: DP
22. Sort Characters By Frequency: Hash Table
23. Interval List Intersections: Two Pointers
24. Construct Binary Search Tree from Preorder Traversal: Binary Search Tree
25. Uncrossed Lines: DP
26. Contiguous Array: Hash Table
27. Possible Bipartition: Bipartite Graph
28. Counting Bits: Math
29. Course Schedule: Topological Sort
30. K Closest Points to Origin: Priority_queue, Sort
31. Edit Distance: DP

30-Day (April) LeetCoding Challenge

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1. Single Number: Bitwise Manipulation
2. Happy Number: Implementation
3. Maximum Subarray: DP
4. Move Zeros: Two pointers
5. Best Time to Buy and Sell Stock II: Greedy
6. Group Anagrams: Hash Table