TagREADME.md

Table of Contents

• String (28)
• Math (17)
• DP (61)
• Double Sequence DP (4)
• BFS (11)
• Segment Tree (1)
• Design (8)
• DFS (32)
• Game Theory (4)
• Hash Table (21)
• Backtracking (13)
• Sort (8)
• Tree (20)
• Trie (7)
• BST (16)
• Permutation (1)
• Partition DP (5)
• Interval DP (4)
• Heap (6)
• Stack (17)
• Linked List (9)
• Binary Indexed Tree (1)
• Graph (5)
• Brainteaser (1)
• Union Find (7)
• Sweep Line (4)
• Interval (1)
• Sequence DP (14)
• Bitwise DP (1)
• MiniMax (1)
• Two Pointers (17)
• Basic Implementation (2)
• Backpack DP (5)
• Bit Manipulation (9)
• Divide and Conquer (6)
• Status DP (1)
• Topological Sort (4)
• Greedy (9)
• Hash Map (1)
• Coordinate DP (12)
• Monotonous Stack (1)
• Binary Tree (6)
• Expression Tree (4)
• Binary Search (25)
• Array (51)
• Memoization (9)
• Two Stacks (1)
• backtracking (1)
• Two Pointer (1)

String (28)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Judge Route Circle.java	Easy	Java	[String]
1	First Unique Character in a String.java	Easy	Java	[Hash Table, String]
2	Reverse Vowels of a String.java	Easy	Java	[String, Two Pointers]
3	Scramble String.java	Hard	Java	[DP, Interval DP, String]
4	Interleaving String.java	Hard	Java	[DP, String]
5	Letter Combinations of a Phone Number.java	Medium	Java	[Backtracking, String]
6	Edit Distance.java	Hard	Java	[DP, Double Sequence DP, String]
7	Distinct Subsequences.java	Hard	Java	[DP, String]
8	Regular Expression Matching.java	Review	Java	[Backtracking, DP, String]
9	Wildcard Matching.java	Hard	Java	[Backtracking, DP, Greedy, String]
10	Add Binary.java	Easy	Java	[Math, String]
11	Longest Substring Without Repeating Characters.java	Medium	Java	[Hash Table, String, Two Pointers]
12	Minimum Window Substring.java	Hard	Java	[Hash Table, String, Two Pointers]
13	Longest Substring with At Most K Distinct Characters.java	Medium	Java	[Hash Table, String]
14	Palindrome Pairs.java	Hard	Java	[Hash Table, String, Trie]
15	Change to Anagram.java	Easy	Java	[String]
16	Compare Version Numbers.java	Medium	Java	[String]
17	Compare Strings.java	Easy	Java	[String]
18	Count and Say.java	Easy	Java	[Basic Implementation, String]
19	One Edit Distance.java	Medium	Java	[String]
20	Decode Ways.java	Medium	Java	[DP, Partition DP, String]
21	Group Anagrams.java	Medium	Java	[Hash Table, String]
22	Flip Game.java	Easy	Java	[String]
23	Implement strStr().java	Easy	Java	[String, Two Pointers]
24	Integer to English Words.java	Hard	Java	[Math, String]
25	Length of Last Word.java	Easy	Java	[String]
26	Longest Common Substring.java	Medium	Java	[DP, Double Sequence DP, String]
27	Longest Words.java	Easy	Java	[Hash Map, String]

Math (17)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Power of Three.java	Easy	Java	[Math]
1	Plus One.java	Easy	Java	[Array, Math]
2	Power of Two.java	Easy	Java	[Bit Manipulation, Math]
3	Encode and Decode TinyURL.java	Medium	Java	[Hash Table, Math]
4	Perfect Squares.java	Medium	Java	[BFS, DP, Math, Partition DP]
5	Valid Perfect Square.java	Review	Java	[Binary Search, Math]
6	Pow(x,n).java	Medium	Java	[Binary Search, Math]
7	Add Binary.java	Easy	Java	[Math, String]
8	Add Digits.java	Easy	Java	[Math]
9	Add Two Numbers.java	Medium	Java	[Linked List, Math]
10	Reverse Integer.java	Easy	Java	[Math]
11	Sqrt(x).java	Easy	Java	[Binary Search, Math]
12	Continuous Subarray Sum.java	Medium	Java	[Coordinate DP, DP, Math]
13	Count Primes.java	Easy	Java	[Hash Table, Math]
14	Excel Sheet Column Number.java	Easy	Java	[Math]
15	Excel Sheet Column Title.java	Easy	Java	[Math]
16	Integer to English Words.java	Hard	Java	[Math, String]

DP (61)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Coin Change.java	Medium	Java	[DP, Memoization, Sequence DP]
1	Maximum Product Subarray.java	Medium	Java	[Array, DP]
2	k Sum.java	Hard	Java	[DP]
3	Longest Increasing Subsequence.java	Medium	Java	[Binary Search, Coordinate DP, DP, Memoization, Sequence DP]
4	Unique Binary Search Tree.java	Medium	Java	[BST, DP, Tree]
5	Unique Paths II.java	Medium	Java	[Array, Coordinate DP, DP]
6	Bomb Enemy.java	Medium	Java	[Coordinate DP, DP]
7	Perfect Squares.java	Medium	Java	[BFS, DP, Math, Partition DP]
8	Backpack VI.java	Medium	Java	[Backpack DP, DP]
9	Copy Books.java	Hard	Java	[Binary Search, DP, Partition DP]
10	Longest Palindromic Subsequence.java	Medium	Java	[DP, Interval DP, Memoization]
11	Scramble String.java	Hard	Java	[DP, Interval DP, String]
12	Best Time to Buy and Sell Stock with Cooldown.java	Medium	Java	[DP]
13	Longest Common Subsequence.java	Medium	Java	[DP, Double Sequence DP]
14	Interleaving String.java	Hard	Java	[DP, String]
15	Edit Distance.java	Hard	Java	[DP, Double Sequence DP, String]
16	Distinct Subsequences.java	Hard	Java	[DP, String]
17	Regular Expression Matching.java	Review	Java	[Backtracking, DP, String]
18	Wildcard Matching.java	Hard	Java	[Backtracking, DP, Greedy, String]
19	Ones and Zeroes.java	Hard	Java	[DP]
20	Word Break II.java	Review	Java	[Backtracking, DP]
21	Unique Path.java	Medium	Java	[Array, Coordinate DP, DP]
22	Maximal Rectangle.java	Hard	Java	[Array, DP, Hash Table, Stack]
23	Maximal Square.java	Medium	Java	[Coordinate DP, DP]
24	Longest Increasing Path in a Matrix.java	Hard	Java	[DFS, DP, Memoization, Topological Sort]
25	Coins in a Line.java	Medium	Java	[DP, Game Theory, Greedy]
26	Coins in a Line II.java	Medium	Java	[Array, DP, Game Theory, Memoization, MiniMax]
27	Climbing Stairs.java	Easy	Java	[DP, Memoization, Sequence DP]
28	Coins in a Line III.java	Hard	Java	[Array, DP, Game Theory, Interval DP, Memoization]
29	Burst Balloons.java	Hard	Java	[DP, Divide and Conquer, Interval DP, Memoization]
30	Nim Game.java	Easy	Java	[Brainteaser, DP, Game Theory]
31	K Edit Distance.java	Hard	Java	[DP, Double Sequence DP, Trie]
32	Jump Game.java	Medium	Java	[Array, DP, Greedy]
33	Coin Change 2.java	Medium	Java	[DP, Sequence DP]
34	Paint House.java	Easy	Java	[DP, Sequence DP]
35	Decode Ways.java	Medium	Java	[DP, Partition DP, String]
36	Longest Continuous Increasing Subsequence.java	Easy	Java	[Array, Coordinate DP, DP]
37	Minimum Path Sum.java	Medium	Java	[Array, Coordinate DP, DP]
38	Counting Bits.java	Medium	Java	[Bit Manipulation, Bitwise DP, DP]
39	Continuous Subarray Sum.java	Medium	Java	[Coordinate DP, DP, Math]
40	House Robber.java	Easy	Java	[DP, Sequence DP]
41	House Robber II.java	Medium	Java	[DP, Sequence DP]
42	House Robber III.java	Medium	Java	[DFS, DP, Status DP, Tree]
43	Paint House II.java	Hard	Java	[DP, Sequence DP]
44	Best Time to Buy and Sell Stock I.java	Easy	Java	[Array, DP, Sequence DP]
45	Best Time to Buy and Sell Stock II.java	Easy	Java	[Array, DP, Greedy, Sequence DP]
46	Best Time to Buy and Sell Stock III .java	Hard	Java	[Array, DP, Sequence DP]
47	Best Time to Buy and Sell Stock IV.java	Hard	Java	[DP, Sequence DP]
48	Russian Doll Envelopes.java	Hard	Java	[Binary Search, Coordinate DP, DP]
49	Jump Game II.java	Hard	Java	[Array, Coordinate DP, DP, Greedy]
50	Backpack.java	Medium	Java	[Backpack DP, DP]
51	Backpack II.java	Medium	Java	[Backpack DP, DP]
52	Backpack V.java	Medium	Java	[Backpack DP, DP]
53	Decode Ways II.java	Hard	Java	[DP, Partition DP]
54	Palindrome Partitioning II.java	Hard	Java	[DP, Partition DP]
55	Backpack III.java	Hard	Java	[Backpack DP, DP]
56	Longest Common Substring.java	Medium	Java	[DP, Double Sequence DP, String]
57	Longest Increasing Continuous subsequence.java	Easy	Java	[Array, Coordinate DP, DP]
58	Longest Increasing Continuous subsequence II.java	Medium	Java	[Array, Coordinate DP, DP, Memoization]
59	Maximum Subarray.java	Easy	Java	[Array, DP, Divide and Conquer, Sequence DP]
60	Maximum Subarray II.java	Medium	Java	[Array, DP, Greedy, Sequence DP]

Double Sequence DP (4)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Longest Common Subsequence.java	Medium	Java	[DP, Double Sequence DP]
1	Edit Distance.java	Hard	Java	[DP, Double Sequence DP, String]
2	K Edit Distance.java	Hard	Java	[DP, Double Sequence DP, Trie]
3	Longest Common Substring.java	Medium	Java	[DP, Double Sequence DP, String]

BFS (11)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Perfect Squares.java	Medium	Java	[BFS, DP, Math, Partition DP]
1	Clone Graph.java	Medium	Java	[BFS, DFS, Graph]
2	Number of Islands.java	Medium	Java	[BFS, DFS, Union Find]
3	Graph Valid Tree.java	Medium	Java	[BFS, DFS, Graph, Union Find]
4	Surrounded Regions.java	Review	Java	[BFS, DFS, Union Find]
5	Trapping Rain Water II.java	Hard	Java	[BFS, Heap]
6	Course Schedule.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
7	Course Schedule II.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
8	Alien Dictionary.java	Hard	Java	[BFS, Backtracking, DFS, Graph, Topological Sort]
9	Binary Tree Preorder Traversal.java	Easy	Java	[BFS, DFS, Stack, Tree]
10	Complete Binary Tree.java	Easy	Java	[BFS, DFS, Tree]

Segment Tree (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Building Outline.java	Review	Java	[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]

Design (9)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Binary Search Tree Iterator.java	Medium	Java	[BST, Design, Stack, Tree]
1	Flatten Nested List Iterator.java	Medium	Java	[Design, Stack]
2	Implement Trie.java	Medium	Java	[Design, Trie]
3	Add and Search Word.java	Medium	Java	[Backtracking, Design, Trie]
4	Data Stream Median.java	Hard	Java	[Design, Heap]
5	Sliding Window Median.java	Hard	Java	[Design, Heap]
6	Min Stack.java	Easy	Java	[Design, Stack]
7	Implement Queue using Stacks.java	Easy	Java	[Design, Stack]
8	Singleton.java	Easy	Java	[Design]

DFS (32)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Nested List Weight Sum.java	Easy	Java	[DFS]
1	Same Tree.java	Easy	Java	[DFS, Tree]
2	Convert Sorted Array to Binary Search Tree.java	Easy	Java	[DFS, Tree]
3	Binary Tree Maximum Path Sum.java	Review	Java	[DFS, Tree]
4	Construct Binary Tree from Inorder and Preorder Traversal.java	Medium	Java	[Array, DFS, Tree]
5	Path Sum.java	Easy	Java	[DFS, Tree]
6	Balanced Binary Tree.java	Medium	Java	[DFS, Tree]
7	Populating Next Right Pointers in Each Node.java	Medium	Java	[DFS, Tree]
8	Validate Binary Search Tree.java	Medium	Java	[BST, DFS, Tree]
9	Convert Sorted List to Binary Search Tree.java	Medium	Java	[DFS, Linked List]
10	Flatten Binary Tree to Linked List.java	Medium	Java	[Binary Tree, DFS]
11	Binary Tree Paths.java	Easy	Java	[Binary Tree, DFS]
12	Clone Graph.java	Medium	Java	[BFS, DFS, Graph]
13	Number of Islands.java	Medium	Java	[BFS, DFS, Union Find]
14	Graph Valid Tree.java	Medium	Java	[BFS, DFS, Graph, Union Find]
15	Surrounded Regions.java	Review	Java	[BFS, DFS, Union Find]
16	Word Search II.java	Hard	Java	[Backtracking, DFS, Trie]
17	Expression Expand.java	Medium	Java	[DFS, Divide and Conquer, Stack]
18	Find Peak Element II.java	Hard	Java	[Binary Search, DFS, Divide and Conquer]
19	Longest Increasing Path in a Matrix.java	Hard	Java	[DFS, DP, Memoization, Topological Sort]
20	Path Sum II.java	Easy	Java	[DFS, Tree]
21	Course Schedule.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
22	Course Schedule II.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
23	Alien Dictionary.java	Hard	Java	[BFS, Backtracking, DFS, Graph, Topological Sort]
24	Binary Tree Preorder Traversal.java	Easy	Java	[BFS, DFS, Stack, Tree]
25	Complete Binary Tree.java	Easy	Java	[BFS, DFS, Tree]
26	House Robber III.java	Medium	Java	[DFS, DP, Status DP, Tree]
27	Palindrome Partitioning.java	Medium	Java	[Backtracking, DFS]
28	Flip Game II.java	Review	Java	[DFS, backtracking]
29	Expression Evaluation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
30	Convert Expression to Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
31	Convert Expression to Reverse Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]

Game Theory (4)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Coins in a Line.java	Medium	Java	[DP, Game Theory, Greedy]
1	Coins in a Line II.java	Medium	Java	[Array, DP, Game Theory, Memoization, MiniMax]
2	Coins in a Line III.java	Hard	Java	[Array, DP, Game Theory, Interval DP, Memoization]
3	Nim Game.java	Easy	Java	[Brainteaser, DP, Game Theory]

Hash Table (21)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Jewels and Stones.java	Easy	Java	[Hash Table]
1	Find Anagram Mappings.java	Easy	Java	[Hash Table]
2	Island Perimeter.java	Easy	Java	[Hash Table]
3	First Unique Character in a String.java	Easy	Java	[Hash Table, String]
4	Encode and Decode TinyURL.java	Medium	Java	[Hash Table, Math]
5	2 Sum.java	Easy	Java	[Array, Hash Table]
6	4 Sum.java	Medium	Java	[Hash Table]
7	Intersection of Two Arrays II.java	Easy	Java	[Binary Search, Hash Table, Sort, Two Pointers]
8	Valid Anagram.java	Easy	Java	[Hash Table, Sort]
9	Longest Substring Without Repeating Characters.java	Medium	Java	[Hash Table, String, Two Pointers]
10	Minimum Window Substring.java	Hard	Java	[Hash Table, String, Two Pointers]
11	Longest Substring with At Most K Distinct Characters.java	Medium	Java	[Hash Table, String]
12	Palindrome Pairs.java	Hard	Java	[Hash Table, String, Trie]
13	Maximal Rectangle.java	Hard	Java	[Array, DP, Hash Table, Stack]
14	Binary Tree Inorder Traversal.java	Easy	Java	[Hash Table, Stack, Tree]
15	Contains Duplicate.java	Easy	Java	[Array, Hash Table]
16	Contains Duplicate II.java	Easy	Java	[Array, Hash Table]
17	Find All Anagrams in a String.java	Easy	Java	[Hash Table]
18	Group Anagrams.java	Medium	Java	[Hash Table, String]
19	Count Primes.java	Easy	Java	[Hash Table, Math]
20	Longest Consecutive Sequence.java	Medium	Java	[Array, Hash Table]

Backtracking (13)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Letter Combinations of a Phone Number.java	Medium	Java	[Backtracking, String]
1	Regular Expression Matching.java	Review	Java	[Backtracking, DP, String]
2	Wildcard Matching.java	Hard	Java	[Backtracking, DP, Greedy, String]
3	Word Break II.java	Review	Java	[Backtracking, DP]
4	Add and Search Word.java	Medium	Java	[Backtracking, Design, Trie]
5	Word Search II.java	Hard	Java	[Backtracking, DFS, Trie]
6	Word Search.java	Medium	Java	[Array, Backtracking]
7	Word Squares.java	Hard	Java	[Backtracking, Trie]
8	Alien Dictionary.java	Hard	Java	[BFS, Backtracking, DFS, Graph, Topological Sort]
9	Palindrome Partitioning.java	Medium	Java	[Backtracking, DFS]
10	Permutations II.java	Medium	Java	[Backtracking]
11	N-Queens.java	Hard	Java	[Backtracking]
12	N-Queens II.java	Hard	Java	[Backtracking]

Sort (8)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Wiggle Sort.java	Medium	Java	[Array, Sort]
1	Intersection of Two Arrays II.java	Easy	Java	[Binary Search, Hash Table, Sort, Two Pointers]
2	Valid Anagram.java	Easy	Java	[Hash Table, Sort]
3	Meeting Rooms.java	Easy	Java	[Sort, Sweep Line]
4	Number of Airplane in the sky.java	Medium	Java	[Array, Interval, Sort, Sweep Line]
5	Meeting Rooms II.java	Medium	Java	[Greedy, Heap, Sort, Sweep Line]
6	Insertion Sort List.java	Medium	Java	[Linked List, Sort]
7	Largest Number.java	Medium	Java	[Sort]

Tree (20)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Unique Binary Search Tree.java	Medium	Java	[BST, DP, Tree]
1	Trim a Binary Search Tree.java	Easy	Java	[BST, Tree]
2	Binary Search Tree Iterator.java	Medium	Java	[BST, Design, Stack, Tree]
3	Same Tree.java	Easy	Java	[DFS, Tree]
4	Convert Sorted Array to Binary Search Tree.java	Easy	Java	[DFS, Tree]
5	Binary Tree Maximum Path Sum.java	Review	Java	[DFS, Tree]
6	Construct Binary Tree from Inorder and Preorder Traversal.java	Medium	Java	[Array, DFS, Tree]
7	Path Sum.java	Easy	Java	[DFS, Tree]
8	Balanced Binary Tree.java	Medium	Java	[DFS, Tree]
9	Populating Next Right Pointers in Each Node.java	Medium	Java	[DFS, Tree]
10	Validate Binary Search Tree.java	Medium	Java	[BST, DFS, Tree]
11	Maximum Binary Tree.java	Medium	Java	[Stack, Tree]
12	Binary Tree Inorder Traversal.java	Easy	Java	[Hash Table, Stack, Tree]
13	Path Sum II.java	Easy	Java	[DFS, Tree]
14	Binary Tree Postorder Traversal.java	Medium	Java	[Stack, Tree, Two Stacks]
15	Closest Binary Search Tree Value.java	Easy	Java	[BST, Binary Search, Tree]
16	Count Complete Tree Nodes.java	Medium	Java	[Binary Search, Tree]
17	Binary Tree Preorder Traversal.java	Easy	Java	[BFS, DFS, Stack, Tree]
18	Complete Binary Tree.java	Easy	Java	[BFS, DFS, Tree]
19	House Robber III.java	Medium	Java	[DFS, DP, Status DP, Tree]

Trie (7)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Maximum XOR of Two Numbers in an Array.java	Medium	Java	[Bit Manipulation, Trie]
1	Implement Trie.java	Medium	Java	[Design, Trie]
2	Add and Search Word.java	Medium	Java	[Backtracking, Design, Trie]
3	Word Search II.java	Hard	Java	[Backtracking, DFS, Trie]
4	Word Squares.java	Hard	Java	[Backtracking, Trie]
5	Palindrome Pairs.java	Hard	Java	[Hash Table, String, Trie]
6	K Edit Distance.java	Hard	Java	[DP, Double Sequence DP, Trie]

BST (16)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Convert Binary Search Tree to Doubly Linked List.java	Medium	Java	[BST]
1	Inorder Successor in Binary Search Tree.java	Medium	Java	[BST]
2	Insert Node in a Binary Search Tree .java	Easy	Java	[BST]
3	Kth Smallest Element in a BST.java	Medium	Java	[BST]
4	Minimum Absolute Difference in BST.java	Easy	Java	[BST]
5	Peeking Iterator.java	Medium	Java	[BST]
6	Remove Node in Binary Search Tree.java	Hard	Java	[BST]
7	Search Range in Binary Search Tree .java	Medium	Java	[BST]
8	Unique Binary Search Tree II.java	Medium	Java	[BST]
9	Zigzag Iterator.java	Medium	Java	[BST]
10	Unique Binary Search Tree.java	Medium	Java	[BST, DP, Tree]
11	Trim a Binary Search Tree.java	Easy	Java	[BST, Tree]
12	Binary Search Tree Iterator.java	Medium	Java	[BST, Design, Stack, Tree]
13	Validate Binary Search Tree.java	Medium	Java	[BST, DFS, Tree]
14	Closest Binary Search Tree Value.java	Easy	Java	[BST, Binary Search, Tree]
15	Contains Duplicate III.java	Medium	Java	[BST]

Permutation (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Shuffle an Array.java	Medium	Java	[Permutation]

Partition DP (5)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Perfect Squares.java	Medium	Java	[BFS, DP, Math, Partition DP]
1	Copy Books.java	Hard	Java	[Binary Search, DP, Partition DP]
2	Decode Ways.java	Medium	Java	[DP, Partition DP, String]
3	Decode Ways II.java	Hard	Java	[DP, Partition DP]
4	Palindrome Partitioning II.java	Hard	Java	[DP, Partition DP]

Interval DP (4)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Longest Palindromic Subsequence.java	Medium	Java	[DP, Interval DP, Memoization]
1	Scramble String.java	Hard	Java	[DP, Interval DP, String]
2	Coins in a Line III.java	Hard	Java	[Array, DP, Game Theory, Interval DP, Memoization]
3	Burst Balloons.java	Hard	Java	[DP, Divide and Conquer, Interval DP, Memoization]

Heap (6)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Kth Smallest Number in Sorted Matrix.java	Medium	Java	[Binary Search, Heap]
1	Trapping Rain Water II.java	Hard	Java	[BFS, Heap]
2	Data Stream Median.java	Hard	Java	[Design, Heap]
3	Sliding Window Median.java	Hard	Java	[Design, Heap]
4	Meeting Rooms II.java	Medium	Java	[Greedy, Heap, Sort, Sweep Line]
5	Building Outline.java	Review	Java	[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]

Stack (17)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Binary Search Tree Iterator.java	Medium	Java	[BST, Design, Stack, Tree]
1	Flatten Nested List Iterator.java	Medium	Java	[Design, Stack]
2	Trapping Rain Water.java	Hard	Java	[Array, Stack, Two Pointers]
3	Min Stack.java	Easy	Java	[Design, Stack]
4	Implement Queue using Stacks.java	Easy	Java	[Design, Stack]
5	Expression Expand.java	Medium	Java	[DFS, Divide and Conquer, Stack]
6	Largest Rectangle in Histogram.java	Hard	Java	[Array, Monotonous Stack, Stack]
7	Maximum Binary Tree.java	Medium	Java	[Stack, Tree]
8	Maximal Rectangle.java	Hard	Java	[Array, DP, Hash Table, Stack]
9	Binary Tree Inorder Traversal.java	Easy	Java	[Hash Table, Stack, Tree]
10	Binary Tree Postorder Traversal.java	Medium	Java	[Stack, Tree, Two Stacks]
11	Binary Tree Preorder Traversal.java	Easy	Java	[BFS, DFS, Stack, Tree]
12	Expression Tree Build.java	Hard	Java	[Binary Tree, Expression Tree, Stack]
13	Expression Evaluation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
14	Convert Expression to Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
15	Convert Expression to Reverse Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
16	Evaluate Reverse Polish Notation.java	Medium	Java	[Stack]

Linked List (10)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Add Two Numbers.java	Medium	Java	[Linked List, Math]
1	Add Two Numbers II.java	Medium	Java	[Linked List]
2	Convert Sorted List to Binary Search Tree.java	Medium	Java	[DFS, Linked List]
3	Linked List Cycle.java	Easy	Java	[Linked List, Two Pointers]
4	Remove Nth Node From End of List.java	Medium	Java	[Linked List, Two Pointers]
5	Linked List Cycle II.java	Medium	Java	[Linked List, Two Pointers]
6	Swap Nodes in Pairs.java	Medium	Java	[Linked List]
7	Delete Node in a Linked List.java	Easy	Java	[Linked List]
8	Insertion Sort List.java	Medium	Java	[Linked List, Sort]
9	Remove Linked List Elements.java	Easy	Java	[Linked List]

Binary Indexed Tree (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Building Outline.java	Review	Java	[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]

Graph (5)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Clone Graph.java	Medium	Java	[BFS, DFS, Graph]
1	Graph Valid Tree.java	Medium	Java	[BFS, DFS, Graph, Union Find]
2	Course Schedule.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
3	Course Schedule II.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
4	Alien Dictionary.java	Hard	Java	[BFS, Backtracking, DFS, Graph, Topological Sort]

Brainteaser (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Nim Game.java	Easy	Java	[Brainteaser, DP, Game Theory]

Union Find (7)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Connecting Graph.java	Medium	Java	[Union Find]
1	Connecting Graph II.java	Medium	Java	[Union Find]
2	Connecting Graph III.java	Medium	Java	[Union Find]
3	Number of Islands.java	Medium	Java	[BFS, DFS, Union Find]
4	Number of Islands II.java	Hard	Java	[Union Find]
5	Graph Valid Tree.java	Medium	Java	[BFS, DFS, Graph, Union Find]
6	Surrounded Regions.java	Review	Java	[BFS, DFS, Union Find]

Sweep Line (4)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Meeting Rooms.java	Easy	Java	[Sort, Sweep Line]
1	Number of Airplane in the sky.java	Medium	Java	[Array, Interval, Sort, Sweep Line]
2	Meeting Rooms II.java	Medium	Java	[Greedy, Heap, Sort, Sweep Line]
3	Building Outline.java	Review	Java	[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]

Interval (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Number of Airplane in the sky.java	Medium	Java	[Array, Interval, Sort, Sweep Line]

Sequence DP (14)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Coin Change.java	Medium	Java	[DP, Memoization, Sequence DP]
1	Longest Increasing Subsequence.java	Medium	Java	[Binary Search, Coordinate DP, DP, Memoization, Sequence DP]
2	Climbing Stairs.java	Easy	Java	[DP, Memoization, Sequence DP]
3	Coin Change 2.java	Medium	Java	[DP, Sequence DP]
4	Paint House.java	Easy	Java	[DP, Sequence DP]
5	House Robber.java	Easy	Java	[DP, Sequence DP]
6	House Robber II.java	Medium	Java	[DP, Sequence DP]
7	Paint House II.java	Hard	Java	[DP, Sequence DP]
8	Best Time to Buy and Sell Stock I.java	Easy	Java	[Array, DP, Sequence DP]
9	Best Time to Buy and Sell Stock II.java	Easy	Java	[Array, DP, Greedy, Sequence DP]
10	Best Time to Buy and Sell Stock III .java	Hard	Java	[Array, DP, Sequence DP]
11	Best Time to Buy and Sell Stock IV.java	Hard	Java	[DP, Sequence DP]
12	Maximum Subarray.java	Easy	Java	[Array, DP, Divide and Conquer, Sequence DP]
13	Maximum Subarray II.java	Medium	Java	[Array, DP, Greedy, Sequence DP]

Bitwise DP (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Counting Bits.java	Medium	Java	[Bit Manipulation, Bitwise DP, DP]

MiniMax (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Coins in a Line II.java	Medium	Java	[Array, DP, Game Theory, Memoization, MiniMax]

Two Pointers (18)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Reverse Vowels of a String.java	Easy	Java	[String, Two Pointers]
1	2 Sum II - Input array is sorted.java	Medium	Java	[Array, Binary Search, Two Pointers]
2	2 Sum II.java	Medium	Java	[Array, Binary Search, Two Pointers]
3	3 Sum Closest.java	Medium	Java	[Array, Two Pointers]
4	3 Sum.java	Medium	Java	[Array, Two Pointers]
5	3 Sum Smaller.java	Medium	Java	[Array, Two Pointers]
6	Intersection of Two Arrays II.java	Easy	Java	[Binary Search, Hash Table, Sort, Two Pointers]
7	Minimum Size Subarray Sum.java	Medium	Java	[Array, Binary Search, Two Pointers]
8	Longest Substring Without Repeating Characters.java	Medium	Java	[Hash Table, String, Two Pointers]
9	Minimum Window Substring.java	Hard	Java	[Hash Table, String, Two Pointers]
10	Linked List Cycle.java	Easy	Java	[Linked List, Two Pointers]
11	Remove Nth Node From End of List.java	Medium	Java	[Linked List, Two Pointers]
12	Linked List Cycle II.java	Medium	Java	[Linked List, Two Pointers]
13	Trapping Rain Water.java	Hard	Java	[Array, Stack, Two Pointers]
14	Find the Duplicate Number.java	Medium	Java	[Array, Binary Search, Two Pointers]
15	Implement strStr().java	Easy	Java	[String, Two Pointers]
16	Interleaving Positive and Negative Numbers.java	Medium	Java	[Two Pointers]
17	Merge Sorted Array.java	Easy	Java	[Array, Two Pointers]

Basic Implementation (2)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Cosine Similarity.java	Easy	Java	[Basic Implementation]
1	Count and Say.java	Easy	Java	[Basic Implementation, String]

Backpack DP (5)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Backpack VI.java	Medium	Java	[Backpack DP, DP]
1	Backpack.java	Medium	Java	[Backpack DP, DP]
2	Backpack II.java	Medium	Java	[Backpack DP, DP]
3	Backpack V.java	Medium	Java	[Backpack DP, DP]
4	Backpack III.java	Hard	Java	[Backpack DP, DP]

Bit Manipulation (9)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Power of Two.java	Easy	Java	[Bit Manipulation, Math]
1	Sum of Two Integers.java	Easy	Java	[Bit Manipulation]
2	Swap Bits.java	Easy	Java	[Bit Manipulation]
3	Update Bits.java	Medium	Java	[Bit Manipulation]
4	Maximum XOR of Two Numbers in an Array.java	Medium	Java	[Bit Manipulation, Trie]
5	Majority Element.java	Easy	Java	[Array, Bit Manipulation, Divide and Conquer]
6	Convert Integer A to Integer B.java	Easy	Java	[Bit Manipulation]
7	Count 1 in Binary.java	Easy	Java	[Bit Manipulation]
8	Counting Bits.java	Medium	Java	[Bit Manipulation, Bitwise DP, DP]

Quick Select (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Median.java	Easy	Java	[Array, Quick Select, Quick Sort]

Divide and Conquer (6)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Majority Element.java	Easy	Java	[Array, Bit Manipulation, Divide and Conquer]
1	Expression Expand.java	Medium	Java	[DFS, Divide and Conquer, Stack]
2	Find Peak Element II.java	Hard	Java	[Binary Search, DFS, Divide and Conquer]
3	Building Outline.java	Review	Java	[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]
4	Burst Balloons.java	Hard	Java	[DP, Divide and Conquer, Interval DP, Memoization]
5	Maximum Subarray.java	Easy	Java	[Array, DP, Divide and Conquer, Sequence DP]

Status DP (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	House Robber III.java	Medium	Java	[DFS, DP, Status DP, Tree]

Topological Sort (4)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Longest Increasing Path in a Matrix.java	Hard	Java	[DFS, DP, Memoization, Topological Sort]
1	Course Schedule.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
2	Course Schedule II.java	Medium	Java	[BFS, DFS, Graph, Topological Sort]
3	Alien Dictionary.java	Hard	Java	[BFS, Backtracking, DFS, Graph, Topological Sort]

Quick Sort (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Median.java	Easy	Java	[Array, Quick Select, Quick Sort]

Greedy (9)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Queue Reconstruction by Height.java	Medium	Java	[Greedy]
1	Wildcard Matching.java	Hard	Java	[Backtracking, DP, Greedy, String]
2	Meeting Rooms II.java	Medium	Java	[Greedy, Heap, Sort, Sweep Line]
3	Coins in a Line.java	Medium	Java	[DP, Game Theory, Greedy]
4	Jump Game.java	Medium	Java	[Array, DP, Greedy]
5	Best Time to Buy and Sell Stock II.java	Easy	Java	[Array, DP, Greedy, Sequence DP]
6	Jump Game II.java	Hard	Java	[Array, Coordinate DP, DP, Greedy]
7	Gas Station.java	Medium	Java	[Greedy]
8	Maximum Subarray II.java	Medium	Java	[Array, DP, Greedy, Sequence DP]

Hash Map (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Longest Words.java	Easy	Java	[Hash Map, String]

Coordinate DP (12)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Longest Increasing Subsequence.java	Medium	Java	[Binary Search, Coordinate DP, DP, Memoization, Sequence DP]
1	Unique Paths II.java	Medium	Java	[Array, Coordinate DP, DP]
2	Bomb Enemy.java	Medium	Java	[Coordinate DP, DP]
3	Unique Path.java	Medium	Java	[Array, Coordinate DP, DP]
4	Maximal Square.java	Medium	Java	[Coordinate DP, DP]
5	Longest Continuous Increasing Subsequence.java	Easy	Java	[Array, Coordinate DP, DP]
6	Minimum Path Sum.java	Medium	Java	[Array, Coordinate DP, DP]
7	Continuous Subarray Sum.java	Medium	Java	[Coordinate DP, DP, Math]
8	Russian Doll Envelopes.java	Hard	Java	[Binary Search, Coordinate DP, DP]
9	Jump Game II.java	Hard	Java	[Array, Coordinate DP, DP, Greedy]
10	Longest Increasing Continuous subsequence.java	Easy	Java	[Array, Coordinate DP, DP]
11	Longest Increasing Continuous subsequence II.java	Medium	Java	[Array, Coordinate DP, DP, Memoization]

Monotonous Stack (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Largest Rectangle in Histogram.java	Hard	Java	[Array, Monotonous Stack, Stack]

Binary Tree (6)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Flatten Binary Tree to Linked List.java	Medium	Java	[Binary Tree, DFS]
1	Binary Tree Paths.java	Easy	Java	[Binary Tree, DFS]
2	Expression Tree Build.java	Hard	Java	[Binary Tree, Expression Tree, Stack]
3	Expression Evaluation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
4	Convert Expression to Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
5	Convert Expression to Reverse Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]

Expression Tree (4)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Expression Tree Build.java	Hard	Java	[Binary Tree, Expression Tree, Stack]
1	Expression Evaluation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
2	Convert Expression to Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]
3	Convert Expression to Reverse Polish Notation.java	Hard	Java	[Binary Tree, DFS, Expression Tree, Stack]

Binary Search (25)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Guess Number Higher or Lower.java	Easy	Java	[Binary Search]
1	2 Sum II - Input array is sorted.java	Medium	Java	[Array, Binary Search, Two Pointers]
2	2 Sum II.java	Medium	Java	[Array, Binary Search, Two Pointers]
3	Longest Increasing Subsequence.java	Medium	Java	[Binary Search, Coordinate DP, DP, Memoization, Sequence DP]
4	Copy Books.java	Hard	Java	[Binary Search, DP, Partition DP]
5	Valid Perfect Square.java	Review	Java	[Binary Search, Math]
6	Intersection of Two Arrays II.java	Easy	Java	[Binary Search, Hash Table, Sort, Two Pointers]
7	Find Peak Element.java	Medium	Java	[Array, Binary Search]
8	Pow(x,n).java	Medium	Java	[Binary Search, Math]
9	Minimum Size Subarray Sum.java	Medium	Java	[Array, Binary Search, Two Pointers]
10	Kth Smallest Number in Sorted Matrix.java	Medium	Java	[Binary Search, Heap]
11	Find Minimum in Rotated Sorted Array.java	Medium	Java	[Array, Binary Search]
12	Find Minimum in Rotated Sorted Array II.java	Hard	Java	[Array, Binary Search]
13	Find Peak Element II.java	Hard	Java	[Binary Search, DFS, Divide and Conquer]
14	Sqrt(x).java	Easy	Java	[Binary Search, Math]
15	First Bad Version.java	Easy	Java	[Binary Search]
16	Wood Cut.java	Medium	Java	[Binary Search]
17	Find the Duplicate Number.java	Medium	Java	[Array, Binary Search, Two Pointers]
18	Maximum Average Subarray II.java	Review	Java	[Array, Binary Search]
19	Classical Binary Search.java	Easy	Java	[Binary Search]
20	Closest Binary Search Tree Value.java	Easy	Java	[BST, Binary Search, Tree]
21	Count Complete Tree Nodes.java	Medium	Java	[Binary Search, Tree]
22	Closest Number in Sorted Array.java	Easy	Java	[Binary Search]
23	Russian Doll Envelopes.java	Hard	Java	[Binary Search, Coordinate DP, DP]
24	Last Position of Target.java	Easy	Java	[Binary Search]

Array (53)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Plus One.java	Easy	Java	[Array, Math]
1	Wiggle Sort.java	Medium	Java	[Array, Sort]
2	2 Sum.java	Easy	Java	[Array, Hash Table]
3	2 Sum II - Input array is sorted.java	Medium	Java	[Array, Binary Search, Two Pointers]
4	2 Sum II.java	Medium	Java	[Array, Binary Search, Two Pointers]
5	Maximum Product Subarray.java	Medium	Java	[Array, DP]
6	3 Sum Closest.java	Medium	Java	[Array, Two Pointers]
7	Triangle Count.java	Medium	Java	[Array]
8	3 Sum.java	Medium	Java	[Array, Two Pointers]
9	Unique Paths II.java	Medium	Java	[Array, Coordinate DP, DP]
10	3 Sum Smaller.java	Medium	Java	[Array, Two Pointers]
11	Array Partition I.java	Easy	Java	[Array]
12	1-bit and 2-bit Characters.java	Easy	Java	[Array]
13	Non-decreasing Array.java	Easy	Java	[Array]
14	Max Consecutive Ones.java	Easy	Java	[Array]
15	Find All Numbers Disappeared in an Array.java	Easy	Java	[Array]
16	Maximum Average Subarray I.java	Easy	Java	[Array]
17	Largest Number At Least Twice of Others.java	Easy	Java	[Array]
18	Toeplitz Matrix.java	Easy	Java	[Array]
19	Find Peak Element.java	Medium	Java	[Array, Binary Search]
20	Majority Element.java	Easy	Java	[Array, Bit Manipulation, Divide and Conquer]
21	Construct Binary Tree from Inorder and Preorder Traversal.java	Medium	Java	[Array, DFS, Tree]
22	Minimum Size Subarray Sum.java	Medium	Java	[Array, Binary Search, Two Pointers]
23	Find Minimum in Rotated Sorted Array.java	Medium	Java	[Array, Binary Search]
24	Find Minimum in Rotated Sorted Array II.java	Hard	Java	[Array, Binary Search]
25	Word Search.java	Medium	Java	[Array, Backtracking]
26	Trapping Rain Water.java	Hard	Java	[Array, Stack, Two Pointers]
27	Largest Rectangle in Histogram.java	Hard	Java	[Array, Monotonous Stack, Stack]
28	Find the Duplicate Number.java	Medium	Java	[Array, Binary Search, Two Pointers]
29	Game of Life.java	Medium	Java	[Array]
30	Maximum Average Subarray II.java	Review	Java	[Array, Binary Search]
31	Number of Airplane in the sky.java	Medium	Java	[Array, Interval, Sort, Sweep Line]
32	Unique Path.java	Medium	Java	[Array, Coordinate DP, DP]
33	Maximal Rectangle.java	Hard	Java	[Array, DP, Hash Table, Stack]
34	Coins in a Line II.java	Medium	Java	[Array, DP, Game Theory, Memoization, MiniMax]
35	Coins in a Line III.java	Hard	Java	[Array, DP, Game Theory, Interval DP, Memoization]
36	Contains Duplicate.java	Easy	Java	[Array, Hash Table]
37	Contains Duplicate II.java	Easy	Java	[Array, Hash Table]
38	Jump Game.java	Medium	Java	[Array, DP, Greedy]
39	Longest Continuous Increasing Subsequence.java	Easy	Java	[Array, Coordinate DP, DP]
40	Minimum Path Sum.java	Medium	Java	[Array, Coordinate DP, DP]
41	Best Time to Buy and Sell Stock I.java	Easy	Java	[Array, DP, Sequence DP]
42	Best Time to Buy and Sell Stock II.java	Easy	Java	[Array, DP, Greedy, Sequence DP]
43	Best Time to Buy and Sell Stock III .java	Hard	Java	[Array, DP, Sequence DP]
44	Jump Game II.java	Hard	Java	[Array, Coordinate DP, DP, Greedy]
45	First Missing Positive.java	Hard	Java	[Array]
46	Longest Consecutive Sequence.java	Medium	Java	[Array, Hash Table]
47	Longest Increasing Continuous subsequence.java	Easy	Java	[Array, Coordinate DP, DP]
48	Longest Increasing Continuous subsequence II.java	Medium	Java	[Array, Coordinate DP, DP, Memoization]
49	Maximum Subarray.java	Easy	Java	[Array, DP, Divide and Conquer, Sequence DP]
50	Maximum Subarray II.java	Medium	Java	[Array, DP, Greedy, Sequence DP]
51	Median.java	Easy	Java	[Array, Quick Select, Quick Sort]
52	Merge Sorted Array.java	Easy	Java	[Array, Two Pointers]

Memoization (9)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Coin Change.java	Medium	Java	[DP, Memoization, Sequence DP]
1	Longest Increasing Subsequence.java	Medium	Java	[Binary Search, Coordinate DP, DP, Memoization, Sequence DP]
2	Longest Palindromic Subsequence.java	Medium	Java	[DP, Interval DP, Memoization]
3	Longest Increasing Path in a Matrix.java	Hard	Java	[DFS, DP, Memoization, Topological Sort]
4	Coins in a Line II.java	Medium	Java	[Array, DP, Game Theory, Memoization, MiniMax]
5	Climbing Stairs.java	Easy	Java	[DP, Memoization, Sequence DP]
6	Coins in a Line III.java	Hard	Java	[Array, DP, Game Theory, Interval DP, Memoization]
7	Burst Balloons.java	Hard	Java	[DP, Divide and Conquer, Interval DP, Memoization]
8	Longest Increasing Continuous subsequence II.java	Medium	Java	[Array, Coordinate DP, DP, Memoization]

Two Stacks (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Binary Tree Postorder Traversal.java	Medium	Java	[Stack, Tree, Two Stacks]

backtracking (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Flip Game II.java	Review	Java	[DFS, backtracking]

Two Pointer (1)

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Permutation in String.java	Medium	Java	[Two Pointer]