Playground for Leetcode Questions.

Trying to solve every question with as many solutions as I can.

Now in Phase II!

• Phase II Review all the questions completed so far, add "code tags" to each of them, try to cover similar questions if necessary.

• Phase I Complete 150 questions.

Question Table

Updating ~~~

1. array

#	***	Name	Code Tags	Groups
1	E	Two Sum	Sort + Two Pointers, Hashtable	K-Sum
15	M	Three Sum	Sort + Two Pointers	K-Sum
18	M	Four Sum	Sort + Two Pointers, Backtracking	K-Sum
167	M	Two Sum Sorted	Sort + Two Pointers, Hashtable, Binary Search	K-Sum
170	E	Two Sum Data Structure	Hashtable	K-Sum
16	M	Three Sum Closest	Sort + Two Pointers	K-Sum
259	M	Three Sum Smaller	Sort + Two Pointers	K-Sum
26	E	Remove Duplicates From Sorted Array	Two Pointers	-
27	E	Remove Element	Two Pointers	-
66	E	Plus One	Math: Carry	-
88	E	Merge Sorted Array	Two Pointers, Reverse Scan, Sentinel	-
118	E	Pascal Triangle	Reverse Scan, Sentinel	Pascal Triangle
119	E	Pascal Triangle 2	Reverse Scan, DP	Pascal Triangle
136	E	Single Number	XOR	Single Number
137	M	Single Number 2	XOR	Single Number
260	M	Single Number 3	XOR	Single Number
169	E	Majority Element	Moore Voting, Hashtable, Sort	Majority Element
229	M	Majority Element 2	Moore Voting, Hashtable	Majority Element
189	E	Rotate Array	Divide & Conquer, Two Pointers	-
191	E	Hamming Weight	Bit Manipulation	Hamming
461	E	Hamming Distance	Bit Manipulation	Hamming
217	E	Contains Duplicate	Hashtable, Sort	Contains Duplicate
219	E	Contains Duplicate 2	Hashtable, Sliding Window	Contains Duplicate
220	M	Contains Duplicate 3	Bucket Sort, TreeSet, Sliding Window	Contains Duplicate
243	E	Shortest Word Distance	Two Pointers, Sentinel	Word Distance
244	M	Shortest Word Distance 2	Two Pointers, Hashtable, String	Word Distance
245	M	Shortest Word Distance 3	Two Pointers	Word Distance
283	E	Move Zeroes	Two Pointers	-
4	H	Median of Two Sorted Arrays	Binary Search, Two Pointers	-
33	H	Search Rotated Array	Binary Search, Two Pointers, Rotation	Rotated Sorted Array
81	M	Search Rotated Array 2	Binary Search, Two Pointers, Rotation	Rotated Sorted Array
153	M	Find Min in Rotated Sorted Array	Binary Search, Two Pointers, Rotation	Rotated Sorted Array
154	H	Find Min in Rotated Sorted Array 2	Binary Search, Two Pointers, Rotation	Rotated Sorted Array
11	M	Container With Most Water	Two Pointers, Early Exit	-
34	M	Search For Range	Binary Search, Two Pointers, Sort	Search Range
35	M	Search Insert Position	Binary Search, Two Pointers	Search Range
278	E	First Bad Version	Binary Search	Search Range
374	E	Guess Number	Binary Search, Ternary Search	Search Range
228	M	Summary Range	Two Pointers, Int2Str	-
268	M	Missing Number	Bit Manipulation, Binary Search	-
287	M	Find Duplicate Number	Binary Search, Two Pointers, Hashtable, Value-as-Index, Sort	Cycle Detection

2. hashtable

#	***	Name	Code Tags	Groups
36	E	Valid Sudoku	HashSet, Matrix Manipulation	-
202	E	Happy Number	HashSet, Two Pointers	-
204	E	Counting Prime	HashSet, Boolean Array, Math	-
205	E	Isomorphic String	HashMap, Value-As-Index	Mapping
290	E	Word Pattern	HashMap, String.split	Mapping
242	E	Valid Anagram	HashMap, Value-As-Index, Sort/Scan	Anagram
49	M	Group Anagrams	HashMap, String Sort	Anagram
438	E	Find Anagram In String	Slide Window, Two Pointers, Value-As-Index	Anagram
246	E	Strobogrammatic Number	HashMap, Two Pointers	-
249	E	Group Shifted String	HashMap, Math	-
266	E	Palindrome Permutation	HashSet, Coin-Flipping, Value-As-Index	Palindrome
267	M	Palindrome Permutation 2	HashMap, Value-As-Index, Backtracking	Palindrome
409	E	Longest Palindrome	HashMap, Coin-Flipping, Value-As-Index	Palindrome
288	E	Unique Abbreviation	HashSet, HashMap	-
299	E	Bulls And Cows	Value-As-Index, Coin-Flipping	-
349	E	Intersection of Arrays	Sort, Two Pointers, Binary Search, HashSet	-
350	E	Intersection of Arrays 2	Sort, HashMap	-
359	E	Logger Rate Limiter	HashMap	-
389	E	Find String Difference	HashMap, Bit Manipulation, Coin-Flipping	-
3	M	Longest Substring Without Repeating Characters	HashMap, Two Pointers, String Scan	-
187	M	Repeated DNA Sequences	HashMap, HashSet, Substring	-
347	M	Top K Frequent Element	Bucket, HashMap, Generic	Frequency
451	M	Sort Characters By Frequency	Bucket, HashMap, Value-As-Index	Frequency

3. linkedlist

#	***	Name	Code Tags	Groups
2	E	Add Two Numbers	Dummy Node, Two Pointers, Sentinel, Math	Add Two Num
445	M	Add Two Numbers 2	Tail Align, Dummy Node, Two Pointers, Sentinel	Add Two Num
369	M	Plus One (Linked List)	Recursion, Reverse, Two Pointers	Add Two Num
19	E	Remove Nth From End	Dummy Node, Recursion, Two Pointers	-
21	E	Merge Sorted Linked List	Dummy Node, Recursion, Sentinel	-
24	E	Swap Nodes in Pairs	Dummy Node, Tri-Pointers, Recursion	-
83	E	Remove Duplicate Nodes	Two Pointers, Recursion	Remove Nodes
82	M	Remove Duplicate Nodes 2	Dummy Node, Two Pointers, Recursion	Remove Nodes
203	E	Remove Element	Node Delete, Dummy Node, Two Pointers	Remove Nodes
237	E	Delete Node	Node Delete	Remove Nodes
141	E	Linked List Cycle	Two Pointers, Floyd Loop Detection, HashSet	Cycle Detection
142	E	Linked List Cycle 2	Two Pointers, Floyd Loop Detection, HashSet	Cycle Detection
160	E	Intersection of Linked List	Two Pointers, Loop Detection, Tail Align, HashSet	-
206	E	Reverse Linked List	Two Pointers, Dummy Node, Recursion	Linkedlist Reverse
92	M	Reverse Linked List 2	Two Pointers, Dummy Node	Linkedlist Reverse
234	E	Palindrome Linked List	Two Pointers, Dummy Node, Recursion	Linkedlist Reverse
143	M	Reorder Linked List	Two Pointers, Reverse	Linkedlist Reverse
61	M	Rotate Linked List	Two Pointers, Loop	-
147	M	Implement Insertion Sort (Linked List)	Two Pointers, Dummy Node, Recursion	Sort
148	M	Implement Merge Sort (Linked List)	Two Pointers, Dummy Node Shift, Cut	Sort
328	M	Odd Even Linked List	Two Pointers, Dummy Node Shift	-