leetcode

The journey of grinding LeetCode.

Top Liked Questions

#	Title	Difficulty	Completed
617	Merge Two Binary Trees	Easy	V
104	Maximum Depth of Binary Tree	Easy	V
136	Single Number	Easy	V
226	Invert Binary Tree	Easy	V
206	Reverse Linked List	Easy	V
283	Move Zeroes	Easy	V
169	Majority Element	Easy	V
448	Find All Numbers Disappeared in an Array	Easy	V
21	Merge Two Sorted Lists	Easy	V
121	Best Time to Buy and Sell Stock	Easy	V
543	Diameter of Binary Tree	Easy	V
70	Climbing Stairs	Easy	V
53	Maximum Subarray	Easy	V
101	Symmetric Tree	Easy	V
1	Two Sum	Easy	V
437	Path Sum III	Easy	V
198	House Robber	Easy	V
155	Min Stack	Easy	V
141	Linked List Cycle	Easy	V
20	Valid Parentheses	Easy	V
234	Palindrome Linked List	Easy	V
160	Intersection of Two Linked Lists	Easy	V
581	Shortest Unsorted Continuous Subarray	Easy	V
338	Counting Bits	Medium	V
406	Queue Reconstruction by Height	Medium	V
739	Daily Temperatures	Medium	V
94	Binary Tree Inorder Traversal	Medium	V
46	Permutations	Medium	V
22	Generate Parentheses	Medium	V
647	Palindromic Substrings	Medium	V
347	Top K Frequent Elements	Medium	V
238	Product of Array Except Self	Medium	V
78	Subsets	Medium	V
48	Rotate Image	Medium	V
39	Combination Sum	Medium	V
49	Group Anagrams	Medium	V
287	Find the Duplicate Number	Medium	V
215	Kth Largest Element in an Array	Medium	V
102	Binary Tree Level Order Traversal	Medium	V
62	Unique Paths	Medium	V
64	Minimum Path Sum	Medium	V
337	House Robber III	Medium	V
96	Unique Binary Search Trees	Medium	V
11	Container With Most Water	Medium	V
394	Decode String	Medium	V
621	Task Scheduler	Medium	V
114	Flatten Binary Tree to Linked List	Medium	V
494	Target Sum	Medium	V
105	Construct Binary Tree from Preorder and Inorder Traversal	Medium	V
309	Best Time to Buy and Sell Stock with Cooldown	Medium	V
17	Letter Combinations of a Phone Number	Medium	V
200	Number of Islands	Medium	V
75	Sort Colors	Medium	V
279	Perfect Squares	Medium	V
208	Implement Trie (Prefix Tree)	Medium	V
560	Subarray Sum Equals K	Medium	V
236	Lowest Common Ancestor of a Binary Tree	Medium	V
240	Search a 2D Matrix II	Medium	V
416	Partition Equal Subset Sum	Medium	V
300	Longest Increasing Subsequence	Medium	V
207	Course Schedule	Medium	V
438	Find All Anagrams in a String	Medium	V
148	Sort List	Medium	V
139	Word Break	Medium	V
56	Merge Intervals	Medium	V
221	Maximal Square	Medium	V
142	Linked List Cycle II	Medium	V
34	Find First and Last Position of Element in Sorted Array	Medium	V
19	Remove Nth Node From End of List	Medium	V
79	Word Search	Medium	V
322	Coin Change	Medium	V
33	Search in Rotated Sorted Array	Medium	V
55	Jump Game	Medium	V
2	Add Two Numbers	Medium	V
138	Copy List with Random Pointer	Medium	V
31	Next Permutation	Medium	V
152	Maximum Product Subarray	Medium	V
146	LRU Cache	Medium	V
3	Longest Substring Without Repeating Characters	Medium	V
5	Longest Palindromic Substring	Medium	V
98	Validate Binary Search Tree	Medium	V
15	3Sum	Medium	V

Top Interview Questions(Easy)

#	Title	Difficulty	Completed
344	Reverse String	Easy	V
104	Maximum Depth of Binary Tree	Easy	V
237	Delete Node in a Linked List	Easy	V
136	Single Number	Easy	V
206	Reverse Linked List	Easy	V
412	Fizz Buzz	Easy	V
108	Convert Sorted Array to Binary Search Tree	Easy	V
169	Majority Element	Easy	V
242	Valid Anagram	Easy	V
122	Best Time to Buy and Sell Stock II	Easy	V
283	Move Zeroes	Easy	V
171	Excel Sheet Column Number	Easy	V
13	Roman to Integer	Easy	V
217	Contains Duplicate	Easy	V
21	Merge Two Sorted Lists	Easy	V
118	Pascal's Triangle	Easy	V
268	Missing Number	Easy	V
191	Number of 1 Bits	Easy	V
387	First Unique Character in a String	Easy	V
350	Intersection of Two Arrays II	Easy	V
121	Best Time to Buy and Sell Stock	Easy	V
202	Happy Number	Easy	V
70	Climbing Stairs	Easy	V
101	Symmetric Tree	Easy	V
53	Maximum Subarray	Easy	V
26	Remove Duplicates from Sorted Array	Easy	V
1	Two Sum	Easy	V
155	Min Stack	Easy	V
160	Intersection of Two Linked Lists	Easy	V
141	Linked List Cycle	Easy	V
66	Plus One	Easy	V
190	Reverse Bits	Easy	V
326	Power of Three	Easy	V
88	Merge Sorted Array	Easy	V
234	Palindrome Linked List	Easy	V
20	Valid Parentheses	Easy	V
172	Factorial Trailing Zeroes	Easy	V
125	Valid Palindrome	Easy	V
14	Longest Common Prefix	Easy	V
28	Implement strStr()	Easy	V
69	Sqrt(x)	Easy	V
204	Count Primes	Easy	V
7	Reverse Integer	Easy	V
230	Kth Smallest Element in a BST	Medium	V

Essential Concepts

• Data Structure:
  • String: string manipulation
  • Array: two pointers, sliding window, searching, in-place modification
  • Tree
  • Graphs
  • Hash Table
    • Chaining
    • Open Addressing
      • Linear Probing
      • Quadratic Hashing
      • Double Hashing
  • Stack
  • Queue
  • Linked List
  • Heap
  • Set
    • Ordered Set
    • UnOrdered Set
  • LRU Cache
  • Ring Buffer
• Problem Solving Techniques:
  • Divide and Conquer
  • Dynamic Programming: Top down / Bottom Up
  • Backtracking
  • Recursion
  • Two Pointers
  • Binary Search
  • Greedy
• Tree Traversal (Recursive/Iterative)
• Search:
  • Binary Search
  • DFS
  • BFS
  • KMP (Knuth–Morris–Pratt algorithm, for string matching)
• Sort:
  • Selection Sort
  • Insertion Sort
  • Bubble Sort
  • Quick Sort
  • Merge Sort
  • Heap Sort
• Graph:
  • Shortest Path
  • Cycle Detection (directed / undirected)
• Bit Manipulation
• Object Oriented Programming
  • Class & Object
  • Access Modifier: public, protected, private
  • Constructor
  • Encapsulation
  • Abstraction
  • Inheritance
  • Polymorphism