Word Break II [LeetCode 151]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: String
Algorithm: dynamic programming, DFS, backtrace, recursively

 

Word Break [LeetCode 150]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: String
Algorithm: recursively, iteratively, dynamic programming, top down

 

Max Points on a Line [LeetCode 149]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: HashMap
Algorithm:

 

Evaluate Reverse Polish Notation [LeetCode 148]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: Array, Stack
Algorithm: one pass strategy

 

Clone Graph [LeetCode 147]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: graph
Algorithm: BFS, DFS

 

Reverse Words in a String [LeetCode 146]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: String
Algorithm:

 

Gas Station [LeetCode 145]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Array
Algorithm: one pass strategy

 

Candy [LeetCode 144]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Array
Algorithm: one pass strategy

 

Sort List [LeetCode 143]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Linked List
Algorithm: divide and conquer

 

Reorder List [LeetCode 142]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Linked List
Algorithm:

 

LRU Cache [LeetCode 141]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: Double Linked List, Hash Map
Algorithm:

 

Linked List Cycle II [LeetCode 140]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Linked List
Algorithm: two pointers

 

Linked List Cycle [LeetCode 139]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: Linked List
Algorithm: two pointers

 

Insertion Sort List [LeetCode 138]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Linked List
Algorithm:

 

Copy List with Random Pointer [LeetCode 137]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: Linked List
Algorithm: Hash

 

Single Number II [LeetCode 136]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Array
Algorithm: bit manipulation

 

Single Number [LeetCode 135]

Frequency: ♥                Difficulty: ♥
Data Structure: Array
Algorithm: hash, bit manipulation

 

Best Time to Buy and Sell Stock III [LeetCode 134]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: Array
Algorithm: divide and conquer, dynamic programming

 

Best Time to Buy and Sell Stock II [LeetCode 133]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: Array
Algorithm: greedy algorithm, one pass strategy

 

Best Time to Buy and Sell Stock [LeetCode 132]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: Array
Algorithm: one pass strategy, dynamic programming

 

Triangle [LeetCode 131]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: matrix
Algorithm: dynamic programming, level order traversal, top-down, bottom-up

 

Pascal’s Triangle II [LeetCode 130]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: ArrayList
Algorithm: level order traversal

 

Pascal’s Triangle [LeetCode 129]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: Array
Algorithm: level order traversal

 

Minimum Depth of Binary Tree [LeetCode 128]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: binary tree
Algorithm: recursively, BFS, level order traversal

 

Maximum Depth of Binary Tree [LeetCode 127]

Frequency: ♥                Difficulty: ♥
Data Structure: binary tree
Algorithm: recursively, BFS, level order traversal

 

Same Tree [LeetCode 126]

Frequency: ♥                Difficulty: ♥
Data Structure: binary tree
Algorithm: recursively

 

Unique Binary Search Trees II [LeetCode 125]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: BST
Algorithm: recursively

 

Unique Binary Search Trees [LeetCode 124]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: binary search tree
Algorithm: dynamic programming, iteratively, recursively

 

Simplify Path [LeetCode 122]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: String, Stack
Algorithm:

 

Permutation Sequence [LeetCode 121]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: Array, String
Algorithm: DFS, math

 

Length of Last Word [LeetCode 120]

Frequency: ♥                Difficulty: ♥
Data Structure: String
Algorithm: one pass strategy

 

Substring with Concatenation of All Words [LeetCode 119]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: String, HashMap, HashSet, Tier Tree
Algorithm:

 

3Sum Closest [LeetCode 118]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Array
Algorithm: two pointers

 

Longest Common Prefix [LeetCode 117]

Frequency: ♥                Difficulty: ♥ ♥
Data Structure: String
Algorithm:

 

ZigZag Conversion [LeetCode 116]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: String
Algorithm: Math

 

Binary Tree Level Order Traversal II [LeetCode 40]

Frequency: ♥                Difficulty: ♥ ♥ ♥
Data Structure: Tree
Algorithm: level traversal

 

Longest Valid Parentheses [LeetCode 23]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥
Data Structure: String, Stack
Algorithm: one pass strategy

 

Word Ladder II [LeetCode 18]

Frequency: ♥                Difficulty: ♥ ♥ ♥ ♥ ♥
Data Structure: String, HashMap, ArrayList, adjacent list, graph
Algorithm: BFS, DFS, backtrace, brute force