Tags

Array

• 1.1 (1) 2 Sum
• 1.2 (167) 2 Sum II - Input array is sorted
• 1.3 (15) 3 Sum
• 1.4 (16) 3 Sum Closest
• 1.5 (259) 3 Sum Smaller
• 1.6 (18) 4 Sum
• 1.7 (4) Median of two Sorted Arrays
• 1.8 (26) Remove Duplicates from Sorted Array
• 1.9 (27) Remove Element
• 1.10 (41) First Missing Positive
• 1.11 (34) Search for a Range
• 1.12 (35) Search Insert Position
• 1.13 (11) Container With Most Water
• 1.14 (31) Next Permutation
• 1.15 (33) Search in Rotated Sorted Array
• 1.16 (39) Combination Sums
• 1.17 (40) Combination SumsII
• 1.18 (42) Trapping Rain Water
• 1.19 (45) Jump Game II
• 1.20 (55) Jump Game
• 1.21 (48) Rotate Image
• 1.22 (53) Maximum Subarray
• 1.23 (54) Spiral Matrix
• 1.24 (56) Merge Intervals
• 1.25 (57) Insert Interval
• 1.26 (59) Spiral Matrix II
• 1.27 (62) Unique Paths
• 1.28 (63) Unique Paths II
• 1.29 (64) Minimum PathsSum
• 1.30 (66) Plus One
• 1.31 (73) Set Matrix Zeroes
• 1.32 (74) Search a 2D Matrix
• 1.33 (75) Sort Colors
• 1.35 (79) Word Search
• 1.36 (80) Remove Duplicates from Sorted Array II
• 1.39 (85) Maximal Rectangle
• 1.40 (88) Merge Sorted Array
• 1.41 (90) Subsets II
• 1.42 (105) Construct Binary Tree from Preorder and Inorder Traversal
• 1.43 (106) Construct Binary Tree from Inorder and Postorder Traversal
• 1.44 (118) Pascal's Triangle
• 1.45 (119) Pascal's Triangle II
• 1.46 (120) Triangle
• 1.47 (121) Best Time to Buy and Sell Stock
• 1.48 (122) Best Time to Buy and Sell Stock II
• 1.49 (123) Best Time to Buy and Sell Stock III
• 1.50 (126) Word Ladder II
• 1.51 (128) Longest Consecutive Sequence
• 1.52 (152) Maximum Product Subarray
• 1.53 (153) Find Minimum in Rotated Sorted Array
• 1.54 (154) Find Minimum in Rotated Sorted Array II
• 1.55 (162) Find Peak Element
• 1.56 (163) Missing Ranges
• 1.57 (169) Majority Element
• 1.58 (189) Rotate Array
• 1.59 (209) Minimum Size Subarray Sum
• 1.60 (216) Combination Sum III
• 1.61 (217) Contains Duplicate
• 1.62 (219) Contains Duplicate II
• 1.63 (220) Contains Duplicate III
• 1.64 (228) Summary Ranges
• 1.65 (229) Majority Element II
• 1.66 (238) Product of Array Except Self
• 1.67 (243) Shortest Word Distance
• 1.68 (245) Shortest Word Distance III
• 1.69 (268) Missing Number
• 1.70 (277) Find the Celebrity
• 1.71 (280) Wiggle Sort
• 1.72 (283) Move Zeroes
• 1.73 (287) Find the Duplicate Number
• 1.74 (289) Game of Life
• 1.75 (370) Range Addition
• 1.76 (380) Insert Delete GetRandom O(1)
• 1.77 (381) Insert Delete GetRandom O(1) - Duplicates allowed
• 1.78 (396) Rotate Function
• 1.79 (414) Third Maximum Number
• 4.24 (454) 4Sum II
• 16.1 (55) Jump Game
• 19.2 (170) Two Sum I I I Data Structure Design

Hash Table

• 1.1 (1) 2 Sum
• 1.6 (18) 4 Sum
• 1.39 (85) Maximal Rectangle
• 1.76 (380) Insert Delete GetRandom O(1)
• 1.77 (381) Insert Delete GetRandom O(1) - Duplicates allowed
• 2.13 (138) Copy List With Random Pointer
• 3.1 (3) Longest Substring Without Repeating Characters
• 3.12 (30) Substring With Concatenation of All Words
• 3.15 (49) Group Anagrams
• 3.21 (76) Minimum Window Substring
• 3.37 (336) Palindrome Pairs
• 4.1 (36) Valid Sudoku
• 4.2 (136) Single Number
• 4.3 (149) Max Points On a Line
• 4.4 (166) Fraction To Recurring Decimal
• 4.5 (187) Repeated D N a Sequences
• 4.6 (202) Happy Number
• 4.7 (204) Count Primes
• 4.8 (205) Isomorphic Strings
• 4.9 (242) Valid Anagram
• 4.10 (246) Strobogrammatic Number
• 4.11 (249) Group Shifted Strings
• 4.12 (269) Alien Dictionary
• 4.13 (274) H Index
• 4.14 (290) Word Pattern
• 4.15 (299) Bulls and Cows
• 4.16 (347) Top K Frequent Elements
• 4.17 (349) Intersection of Two Arrays
• 4.18 (350) Intersection of Two Arrays II
• 4.19 (355) Design Twitter
• 4.20 (389) Find The Difference
• 4.21 (409) Longest Palindrome
• 4.22 (438) Find All Anagrams in a String
• 4.23 (447) Number of Boomerangs
• 4.24 (454) 4Sum II
• 10.1 (94) Binary Tree Inorder Traversal
• 13.1 (37) Sudoku Solver

BinarySearch

• 1.2 (167) 2 Sum II - Input array is sorted
• 1.4 (16) 3 Sum Closest
• 1.5 (259) 3 Sum Smaller
• 1.8 (26) Remove Duplicates from Sorted Array
• 1.9 (27) Remove Element
• 1.10 (41) First Missing Positive
• 1.11 (34) Search for a Range
• 1.12 (35) Search Insert Position
• 1.13 (11) Container With Most Water
• 1.14 (31) Next Permutation
• 1.15 (33) Search in Rotated Sorted Array
• 1.32 (74) Search a 2D Matrix

Two Pointers

• 1.3 (15) 3 Sum
• 1.6 (18) 4 Sum
• 1.33 (75) Sort Colors
• 1.36 (80) Remove Duplicates from Sorted Array II
• 1.59 (209) Minimum Size Subarray Sum
• 1.60 (216) Combination Sum III
• 1.72 (283) Move Zeroes
• 2.2 (19) Remove Nth Node
• 2.7 (61) Rotate List
• 2.10 (86) Partition List
• 2.14 (141) Linked List Cycle
• 2.15 (142) Linked List Cycle II
• 2.22 (234) Palindrome Linked List
• 3.1 (3) Longest Substring Without Repeating Characters
• 3.11 (28) Implementstr Str
• 3.12 (30) Substring With Concatenation of All Words
• 3.21 (76) Minimum Window Substring
• 3.24 (125) Valid Palindrome
• 3.38 (344) Reverse String
• 3.39 (345) Reverse Vowels of a String
• 4.10 (246) Strobogrammatic Number
• 4.17 (349) Intersection of Two Arrays
• 4.18 (350) Intersection of Two Arrays II

Binary Search

• 1.7 (4) Median of two Sorted Arrays
• 1.53 (153) Find Minimum in Rotated Sorted Array
• 1.54 (154) Find Minimum in Rotated Sorted Array II
• 1.55 (162) Find Peak Element
• 1.59 (209) Minimum Size Subarray Sum
• 1.60 (216) Combination Sum III
• 4.17 (349) Intersection of Two Arrays
• 4.18 (350) Intersection of Two Arrays II
• 4.24 (454) 4Sum II
• 10.27 (222) Count Complete Tree Nodes
• 10.29 (230) Kth Smallest Element Ina B S T
• 11.1 (29) Divide Two Integers
• 11.2 (50) Pow X N
• 11.3 (69) Sqrtx
• 11.4 (240) Search a 2 D Matrix II
• 11.5 (275) H Index II
• 11.6 (278) First Bad Version
• 11.7 (367) Valid Perfect Square
• 11.8 (374) Guess Number Higher Or Lower
• 11.9 (378) Kth Smallest Element in a Sorted Matrix
• 11.10 (436) Find Right Interval
• 11.11 (441) Arranging Coins
• 15.15 (174) Dungeon Game
• 15.25 (300) Longest Increasing Subsequence
• 15.38 (354) Russian Doll Envelopes
• 15.40 (363) Max Sum of Rectangle No Larger Than K
• 15.45 (392) Is Subsequence
• 15.48 (410) Split Array Largest Sum

Divide and Conquer

• 1.7 (4) Median of two Sorted Arrays
• 1.57 (169) Majority Element
• 2.4 (23) Merge K Sorted Lists
• 7.1 (215) Kth Largest Element in an Array
• 10.25 (218) The Skyline Problem
• 10.42 (315) Count of Smaller Numbers After Self
• 10.43 (327) Count of Range Sum
• 11.4 (240) Search a 2 D Matrix II
• 14.1 (241) Different Ways To Add Parentheses
• 14.2 (282) Expression Add Operators
• 15.29 (312) Burst Balloons

Backtrack

• 1.16 (39) Combination Sums
• 1.17 (40) Combination SumsII
• 1.18 (42) Trapping Rain Water

Greedy

• 1.19 (45) Jump Game II
• 1.20 (55) Jump Game
• 1.48 (122) Best Time to Buy and Sell Stock II
• 15.3 (44) Wildcard Matching
• 15.31 (321) Create Maximum Number
• 15.43 (376) Wiggle Subsequence
• 15.45 (392) Is Subsequence
• 16.1 (55) Jump Game
• 16.2 (134) Gas Station
• 16.3 (135) Candy
• 16.4 (316) Remove Duplicate Letters
• 16.5 (330) Patching Array
• 16.6 (402) Remove K Digits
• 16.7 (406) Queue Reconstruction By Height
• 16.8 (435) Non Overlapping Intervals
• 16.9 (452) Minimum Number of Arrows To Burst Balloons

DP

• 1.19 (45) Jump Game II
• 1.27 (62) Unique Paths
• 1.28 (63) Unique Paths II
• 1.29 (64) Minimum PathsSum
• 1.39 (85) Maximal Rectangle
• 3.26 (139) Word Break
• 15. Dynamic Programming

Dynamic Programming

• 1.22 (53) Maximum Subarray
• 1.46 (120) Triangle
• 1.47 (121) Best Time to Buy and Sell Stock
• 1.49 (123) Best Time to Buy and Sell Stock III
• 1.50 (126) Word Ladder II
• 1.52 (152) Maximum Product Subarray
• 14.1 (10) Regular Express Match
• 15.2 (32) Longest Valid Parentheses
• 15.3 (44) Wildcard Matching
• 15.4 (70) Climbing Stairs
• 15.5 (72) Edit Distance
• 15.6 (87) Scramble String
• 15.7 (91) Decode Ways
• 15.8 (95) Unique Binary Search Trees II
• 15.9 (96) Unique Binary Search Trees
• 15.10 (115) Distinct Subsequences
• 15.11 (127) Word Ladder
• 15.12 (140) Word Break II
• 15.13 (159) Longest Substring With At Most Two Distinct Characters
• 15.14 (161) One Edit Distance
• 15.15 (174) Dungeon Game
• 15.16 (188) Best Timeto Buy and Sell Stock IV
• 15.17 (198) House Robber
• 15.18 (213) House Robber II
• 15.19 (221) Maximal Square
• 15.20 (244) Shortest Worddistance II
• 15.21 (256) Paint House
• 15.22 (264) Ugly Number II
• 15.23 (265) Paint House II
• 15.24 (279) Perfect Squares
• 15.25 (300) Longest Increasing Subsequence
• 15.26 (303) Range Sum Query Immutable
• 15.27 (304) Range Sum Query 2 D Immutable
• 15.28 (309) Best Time To Buy and Sell Stock With Cooldown
• 15.29 (312) Burst Balloons
• 15.30 (317) Shortest Distance From All Buildings
• 15.31 (321) Create Maximum Number
• 15.32 (322) Coin Change
• 15.33 (325) Maximum Size Subarray Sum Equals K
• 15.34 (334) Increasing Triplet Subsequence
• 15.35 (338) Counting Bits
• 15.36 (340) Longest Substring With At Most K Distinct Characters
• 15.37 (343) Integer Break
• 15.38 (354) Russian Doll Envelopes
• 15.39 (357) Count Numbers With Unique Digits
• 15.40 (363) Max Sum of Rectangle No Larger Than K
• 15.41 (368) Largest Divisible Subset
• 15.42 (375) Guess Number Higher Or Lower II
• 15.43 (376) Wiggle Subsequence
• 15.44 (377) Combination Sum IV
• 15.45 (392) Is Subsequence
• 15.46 (395) Longest Substring With At Least K Repeating Characters
• 15.47 (403) Frog Jump
• 15.48 (410) Split Array Largest Sum
• 15.49 (411) Minimum Unique Word Abbreviation
• 15.50 (413) Arithmetic Slices
• 15.51 (416) Partition Equal Subset Sum
• 15.52 (424) Longest Repeating Character Replacement
• 15.53 (446) Arithmetic Slices II Subsequence

Math

• 1.30 (66) Plus One
• 1.69 (268) Missing Number
• 1.78 (396) Rotate Function
• 2.1 (2) Add Two Numbers
• 3.4 (8) String To Integer
• 3.5 (12) Integer To Roman
• 3.6 (13) Roman To Integer
• 3.14 (43) Multiply Strings
• 3.17 (65) Valid Number
• 3.18 (67) Add Binary
• 3.35 (273) Integer To English Words
• 4.3 (149) Max Points On a Line
• 4.4 (166) Fraction To Recurring Decimal
• 4.6 (202) Happy Number
• 4.7 (204) Count Primes
• 5.3 (224) Basic Calculator
• 7.4 (313) Super Ugly Number
• 7.5 (360) Sort Transformed Array
• 9.5 (231) Power of Two
• 9.11 (397) Integer Replacement
• 11.1 (29) Divide Two Integers
• 11.2 (50) Pow X N
• 11.3 (69) Sqrtx
• 11.7 (367) Valid Perfect Square
• 11.11 (441) Arranging Coins
• 13.6 (60) Permutation Sequence
• 15.22 (264) Ugly Number II
• 15.24 (279) Perfect Squares
• 15.37 (343) Integer Break
• 15.39 (357) Count Numbers With Unique Digits
• 15.41 (368) Largest Divisible Subset
• 15.50 (413) Arithmetic Slices
• 18.1 (7) Reverse Integer
• 18.2 (9) Palindrome Number
• 18.3 (168) Excel Sheet Column Title
• 18.4 (171) Excel Sheet Column Number
• 18.5 (172) Factorial Trailing Zeroes
• 18.6 (223) Rectangle Area
• 18.7 (233) Number of Digit One
• 18.8 (258) Add Digits
• 18.9 (263) Ugly Number
• 18.10 (306) Additive Number
• 18.11 (319) Bulb Switcher
• 18.12 (326) Power of Three
• 18.13 (335) Self Crossing
• 18.14 (365) Water and Jug Problem
• 18.15 (372) Super Pow
• 18.16 (400) Nth Digit
• 18.17 (415) Add Strings
• 18.18 (423) Reconstruct Original Digits From English
• 18.19 (453) Minimum Moves To Equal Array Elements

Matrix

• 1.31 (73) Set Matrix Zeroes
• 1.32 (74) Search a 2D Matrix

Sort

• 1.33 (75) Sort Colors
• 2.17 (147) Insertion Sort List
• 2.18 (148) Sort List
• 4.9 (242) Valid Anagram
• 4.13 (274) H Index
• 4.17 (349) Intersection of Two Arrays
• 4.18 (350) Intersection of Two Arrays II
• 17.1 (163) Maximum Gap
• 17.2 (179) Largest Number
• 17.3 (324) Wiggle Sort II
• 17.4 (331) Verify Preorder Serialization of a Binary Tree

Backtracking

• 1.35 (79) Word Search
• 3.8 (17) Letter Combination
• 3.10 (22) Generate Parentheses
• 3.22 (93) Restore I P Addresses
• 3.23 (97) Interleaving String
• 13.1 (37) Sudoku Solver
• 13.2 (46) Permutations
• 13.3 (47) Permutations II
• 13.4 (51) N Queens
• 13.5 (52) N Queens II
• 13.6 (60) Permutation Sequence
• 13.7 (77) Combinations
• 13.8 (89) Gray Code
• 13.9 (131) Palindrome Partitioning
• 13.10 (211) Add and Search Word Data Structure Design
• 13.11 (212) Word Search II
• 13.12 (254) Factor Combinations
• 13.13 (266) Palindrome Permutation
• 13.14 (267) Palindrome Permutation II
• 13.15 (401) Binary Watch
• 14.1 (10) Regular Express Match
• 15.3 (44) Wildcard Matching
• 15.12 (140) Word Break II
• 15.39 (357) Count Numbers With Unique Digits

DFS

• 1.35 (79) Word Search
• 1.42 (105) Construct Binary Tree from Preorder and Inorder Traversal
• 1.43 (106) Construct Binary Tree from Inorder and Postorder Traversal
• 2.12 (109) Convert Sorted List To Binary Search Tree
• 5.7 (394) Decode String
• 10.2 (98) Validate Binary Search Tree
• 10.3 (99) Recover Binary Search Tree
• 10.4 (100) Same Tree
• 10.8 (104) Maximum Depthof Binary Tree
• 10.10 (108) Convert Sorted Array To Binary Search Tree
• 10.11 (110) Balanced Binary Tree
• 10.12 (111) Minimum Depthof Binary Tree
• 10.13 (112) Path Sum
• 10.14 (113) Path Sum II
• 10.15 (114) Flatten Binary Tree To Linked List
• 10.16 (116) Populating Next Right Pointers in Each Node
• 10.17 (117) Populating Next Right Pointers in Each Node II
• 10.18 (124) Binary Tree Maximum Path Sum
• 10.19 (129) Sum Root To Leaf Numbers
• 10.24 (199) Binary Tree Right Side View
• 10.34 (257) Binary Tree Paths
• 10.45 (337) House Robber II I
• 12.2 (133) Clone Graph
• 12.3 (200) Number of Islands
• 12.4 (207) Course Schedule
• 12.5 (210) Course Schedule II
• 12.6 (301) Remove Invalid Parentheses
• 12.8 (329) Longest Increasing Path in a Matrix
• 12.9 (332) Reconstruct Itinerary
• 12.10 (417) Pacific Atlantic Water Flow

Stack

• 1.39 (85) Maximal Rectangle
• 3.9 (20) Valid Parentheses
• 3.42 (385) Mini Parser
• 5.1 (150) Evaluate Reverse Polish Notation
• 5.2 (155) Min Stack
• 5.3 (224) Basic Calculator
• 5.4 (225) Implement Stack Using Queues
• 5.5 (232) Implement Queue Using Stacks
• 5.6 (341) Flatten Nested List Iterator
• 5.7 (394) Decode String
• 10.1 (94) Binary Tree Inorder Traversal
• 10.7 (103) Binary Tree Zigzag Level Order Traversal
• 10.20 (144) Binary Tree Preorder Traversal
• 10.21 (145) Binary Tree Postorder Traversal
• 10.23 (173) Binary Search Tree Iterator
• 16.4 (316) Remove Duplicate Letters
• 16.6 (402) Remove K Digits

Tree

• 1.42 (105) Construct Binary Tree from Preorder and Inorder Traversal
• 1.43 (106) Construct Binary Tree from Inorder and Postorder Traversal
• 10.1 (94) Binary Tree Inorder Traversal
• 10.2 (98) Validate Binary Search Tree
• 10.3 (99) Recover Binary Search Tree
• 10.4 (100) Same Tree
• 10.5 (101) Symmetric Tree
• 10.6 (102) Binary Tree Level Order Traversal
• 10.7 (103) Binary Tree Zigzag Level Order Traversal
• 10.8 (104) Maximum Depthof Binary Tree
• 10.9 (107) Binary Tree Level Order Traversal II
• 10.10 (108) Convert Sorted Array To Binary Search Tree
• 10.11 (110) Balanced Binary Tree
• 10.12 (111) Minimum Depthof Binary Tree
• 10.13 (112) Path Sum
• 10.14 (113) Path Sum II
• 10.15 (114) Flatten Binary Tree To Linked List
• 10.16 (116) Populating Next Right Pointers in Each Node
• 10.17 (117) Populating Next Right Pointers in Each Node II
• 10.18 (124) Binary Tree Maximum Path Sum
• 10.19 (129) Sum Root To Leaf Numbers
• 10.20 (144) Binary Tree Preorder Traversal
• 10.21 (145) Binary Tree Postorder Traversal
• 10.23 (173) Binary Search Tree Iterator
• 10.24 (199) Binary Tree Right Side View
• 10.27 (222) Count Complete Tree Nodes
• 10.28 (226) Invert Binary Tree
• 10.29 (230) Kth Smallest Element Ina B S T
• 10.30 (235) Lowest Common Ancestor of a Binary Search Tree
• 10.31 (236) Lowest Common Ancestor of a Binary Tree
• 10.32 (250) Count Univalue Subtrees
• 10.34 (257) Binary Tree Paths
• 10.38 (297) Serialize and Deserialize Binary Tree
• 10.44 (333) Largest B S T Subtree
• 10.45 (337) House Robber II I
• 10.48 (404) Sum of Left Leaves
• 10.49 (437) Path Sum II I
• 15.8 (95) Unique Binary Search Trees II
• 15.9 (96) Unique Binary Search Trees

Union Find

• 1.51 (128) Longest Consecutive Sequence
• 12.1 (130) Surrounded Regions
• 12.3 (200) Number of Islands

Bit Manipulation

• 1.57 (169) Majority Element
• 1.69 (268) Missing Number
• 4.2 (136) Single Number
• 4.5 (187) Repeated D N a Sequences
• 4.20 (389) Find The Difference
• 9.1 (137) Single Number II
• 9.2 (190) Reverse Bits
• 9.3 (191) Number of 1 Bits
• 9.4 (201) Bitwise and of Numbers Range
• 9.5 (231) Power of Two
• 9.6 (260) Single Number II I
• 9.7 (318) Maximum Product of Word Lengths
• 9.8 (342) Power of Four
• 9.9 (371) Sum of Two Integers
• 9.10 (393) UTF8 Validation
• 9.11 (397) Integer Replacement
• 9.12 (405) Convert a Number To Hexadecimal
• 9.13 (421) Maximum XOR of Two Numbers in an Array
• 13.15 (401) Binary Watch
• 15.35 (338) Counting Bits

Hash Tables

• 1.61 (217) Contains Duplicate
• 1.62 (219) Contains Duplicate II

Binary Search Tree

• 1.63 (220) Contains Duplicate III
• 10.26 (220) Contain Duplicate II I
• 10.36 (272) Closest Binary Search Tree Value II
• 10.37 (285) Inorder Successor in B S T
• 10.42 (315) Count of Smaller Numbers After Self
• 10.43 (327) Count of Range Sum
• 10.46 (352) Data Stream As Disjoint Intervals

Design

• 1.76 (380) Insert Delete GetRandom O(1)
• 1.77 (381) Insert Delete GetRandom O(1) - Duplicates allowed
• 4.19 (355) Design Twitter
• 5.2 (155) Min Stack
• 5.4 (225) Implement Stack Using Queues
• 5.5 (232) Implement Queue Using Stacks
• 5.6 (341) Flatten Nested List Iterator
• 7.3 (295) Find Median From Data Stream
• 10.23 (173) Binary Search Tree Iterator
• 10.38 (297) Serialize and Deserialize Binary Tree
• 13.10 (211) Add and Search Word Data Structure Design
• 15.20 (244) Shortest Worddistance II
• 19.1 (146) LRU
• 19.2 (170) Two Sum I I I Data Structure Design
• 19.3 (208) Implement Trie Prefix Tree
• 19.4 (251) Flatten 2 D Vector
• 19.5 (281) Zigzag Iterator
• 19.6 (284) Peeking Iterator
• 19.7 (293) Flip Game
• 19.8 (294) Flip Game I I
• 19.9 (348) Design Tic Tac Toe
• 19.10 (351) Android Unlock Patterns
• 19.11 (353) Design Snake Game
• 19.12 (359) Logger Rate Limiter
• 19.13 (362) Design Hit Counter
• 19.14 (379) Design Phone Directory
• 19.15 (390) Elimination Game
• 19.16 (420) Strong Password Checker
• 19.17 (432) All Oone Data Structure
• 19.18 (439) Ternary Expression Parser
• 19.19 (444) Sequence Reconstruction

Linked List

• 2.1 (2) Add Two Numbers
• 2.2 (19) Remove Nth Node
• 2.3 (21) Merge Two Sorted Lists
• 2.4 (23) Merge K Sorted Lists
• 2.5 (24) Swap Nodes in Pair
• 2.6 (25) Reverse Nodes in K Group
• 2.7 (61) Rotate List
• 2.8 (82) Remove Duplicates From Sorted List II
• 2.9 (83) Remove Duplicates From Sorted List
• 2.10 (86) Partition List
• 2.11 (92) Reverse Linked List II
• 2.12 (109) Convert Sorted List To Binary Search Tree
• 2.13 (138) Copy List With Random Pointer
• 2.14 (141) Linked List Cycle
• 2.15 (142) Linked List Cycle II
• 2.16 (143) Reorder List
• 2.17 (147) Insertion Sort List
• 2.18 (148) Sort List
• 2.19 (160) Intersection of Two Linked Lists
• 2.20 (203) Remove Linked List Elements
• 2.21 (206) Reverse Linked List
• 2.22 (234) Palindrome Linked List
• 2.23 (237) Delete Node in a Linked List
• 2.24 (328) Odd Even Linked List
• 2.25 (369) Plus One Linked List

Heap

• 2.4 (23) Merge K Sorted Lists
• 4.16 (347) Top K Frequent Elements
• 4.19 (355) Design Twitter
• 7.1 (215) Kth Largest Element in an Array
• 7.2 (239) Sliding Window Maximum
• 7.3 (295) Find Median From Data Stream
• 7.4 (313) Super Ugly Number
• 7.5 (360) Sort Transformed Array
• 7.6 (373) Find K Pairs With Smallest Sums
• 7.7 (407) Trapping Rain Water II
• 10.25 (218) The Skyline Problem
• 11.9 (378) Kth Smallest Element in a Sorted Matrix
• 15.22 (264) Ugly Number II

String

• 3.1 (3) Longest Substring Without Repeating Characters
• 3.2 (5) Longest Palindromic Substring
• 3.3 (6) Zig Zag Conversion
• 3.4 (8) String To Integer
• 3.5 (12) Integer To Roman
• 3.6 (13) Roman To Integer
• 3.7 (14) Longest Common Prefix
• 3.8 (17) Letter Combination
• 3.9 (20) Valid Parentheses
• 3.10 (22) Generate Parentheses
• 3.11 (28) Implementstr Str
• 3.12 (30) Substring With Concatenation of All Words
• 3.13 (38) Count and Say
• 3.14 (43) Multiply Strings
• 3.15 (49) Group Anagrams
• 3.16 (58) Length of Last Word
• 3.17 (65) Valid Number
• 3.18 (67) Add Binary
• 3.19 (68) Text Justification
• 3.20 (71) Simplify Path
• 3.21 (76) Minimum Window Substring
• 3.22 (93) Restore I P Addresses
• 3.23 (97) Interleaving String
• 3.24 (125) Valid Palindrome
• 3.25 (132) Palindrome Partitioning II
• 3.26 (139) Word Break
• 3.27 (151) Reverse Words in String
• 3.28 (157) Read N Characters Given Read 4
• 3.29 (158) Read N Characters Given Read 4 II
• 3.30 (165) Compare Version Number
• 3.31 (186) Reverse Words Ina String II
• 3.32 (214) Shortest Palindrome
• 3.33 (227) Basic Calculator II
• 3.34 (271) Encode and Decode Strings
• 3.35 (273) Integer To English Words
• 3.36 (291) Word Pattern II
• 3.37 (336) Palindrome Pairs
• 3.38 (344) Reverse String
• 3.39 (345) Reverse Vowels of a String
• 3.40 (358) Rearrange String K Distance Apart
• 3.41 (383) Ransom Note
• 3.42 (385) Mini Parser
• 3.43 (387) First Unique Character in a String
• 3.44 (388) Longest Absolute File Path
• 3.45 (408) Valid Word Abbreviation
• 14.1 (10) Regular Express Match
• 15.2 (32) Longest Valid Parentheses
• 15.3 (44) Wildcard Matching
• 15.5 (72) Edit Distance
• 15.6 (87) Scramble String
• 15.7 (91) Decode Ways
• 15.14 (161) One Edit Distance
• 15.36 (340) Longest Substring With At Most K Distinct Characters
• 15.49 (411) Minimum Unique Word Abbreviation

Trie

• 3.37 (336) Palindrome Pairs
• 9.13 (421) Maximum XOR of Two Numbers in an Array
• 13.10 (211) Add and Search Word Data Structure Design
• 13.11 (212) Word Search II
• 19.3 (208) Implement Trie Prefix Tree

Queue

• 6.1 (346) Moving Average From Data Stream
• 15.40 (363) Max Sum of Rectangle No Larger Than K

queue

• 7.2 (239) Sliding Window Maximum

BFS

• 7.7 (407) Trapping Rain Water II
• 10.6 (102) Binary Tree Level Order Traversal
• 10.7 (103) Binary Tree Zigzag Level Order Traversal
• 10.9 (107) Binary Tree Level Order Traversal II
• 10.12 (111) Minimum Depthof Binary Tree
• 10.24 (199) Binary Tree Right Side View
• 12.1 (130) Surrounded Regions
• 12.2 (133) Clone Graph
• 12.3 (200) Number of Islands
• 12.4 (207) Course Schedule
• 12.5 (210) Course Schedule II
• 12.6 (301) Remove Invalid Parentheses
• 12.7 (310) Minimum Height Trees
• 12.10 (417) Pacific Atlantic Water Flow
• 15.24 (279) Perfect Squares

Graph

• 8.1 (261) Graph Valid Tree
• 8.2 (323) Number of Connected Components in an Undirected Grap
• 8.3 (399) Evaluate Division
• 12.2 (133) Clone Graph
• 12.4 (207) Course Schedule
• 12.5 (210) Course Schedule II
• 12.7 (310) Minimum Height Trees
• 12.9 (332) Reconstruct Itinerary

Binary Tree

• 10.22 (156) Binary Tree Upside Down
• 10.33 (255) Verify Preorder Sequence in Binary Search Tree
• 10.35 (270) Closest Binary Search Tree Value
• 10.39 (298) Binary Tree Longest Consecutive Sequence
• 10.41 (314) Binary Tree Vertical Order Traversal
• 10.47 (366) Find Leaves of Binary Tree

Binary Indexed Tree

• 10.25 (218) The Skyline Problem
• 10.42 (315) Count of Smaller Numbers After Self

Segment Tree

• 10.25 (218) The Skyline Problem
• 10.40 (307) Range Sum Query Mutable
• 10.42 (315) Count of Smaller Numbers After Self

Binary Index Tree

• 10.40 (307) Range Sum Query Mutable

Topological Sort

• 12.4 (207) Course Schedule
• 12.5 (210) Course Schedule II
• 12.8 (329) Longest Increasing Path in a Matrix

Memoization

• 12.8 (329) Longest Increasing Path in a Matrix

Brainteaser

• 18.11 (319) Bulb Switcher
• 20.10 (292) Nim Game

Other

• 20.1 (247) Strobogrammatic Number I I
• 20.2 (248) Strobogrammatic Number I I I
• 20.3 (252) Meeting Rooms
• 20.4 (253) Meeting Rooms I I
• 20.5 (259) 3 Sum Smaller
• 20.6 (276) Paint Fence
• 20.7 (277) Find The Celebrity
• 20.8 (286) Walls and Gates
• 20.9 (288) Unique Word Abbreviation
• 20.10 (292) Nim Game
• 20.11 (296) Best Meeting Point
• 20.12 (302) Smallest Rectangle Enclosing Black Pixels
• 20.13 (305) Number of Islands I I
• 20.14 (308) Range Sum Query 2 D Mutable
• 20.15 (311) Sparse Matrix Multiplication
• 20.16 (320) Generalized Abbreviation
• 20.17 (339) Nested List Weight Sum
• 20.19 (356) Line Reflection
• 20.20 (361) Bomb Enemy
• 20.21 (364) Nested List Weight Sum I I
• 20.22 (382) Linked List Random Node
• 20.23 (384) Shuffle an Array
• 20.24 (386) Lexicographical Numbers
• 20.25 (391) Perfect Rectangle
• 20.26 (398) Random Pick Index
• 20.27 (412) Fizz Buzz
• 20.28 (418) Sentence Screen Fitting
• 20.29 (419) Battleships in a Board
• 20.30 (422) Valid Word Square
• 20.31 (425) Word Squares
• 20.32 (440) Kth Smallest in Lexicographical Order

Reservoir Sampling

• 20.22 (382) Linked List Random Node
• 20.26 (398) Random Pick Index

SQL

• 21.1 (175) Combine Two Tables
• 21.2 (176) Second Highest Salary
• 21.4 (178) Rank Scores
• 21.5 (180) Consecutive Number
• 21.6 (181) Employees Earning More Than Their Manager
• 21.7 (182) Duplicate Emails
• 21.8 (183) Customers Who Never Order
• 21.9 (184) Department Highest Salary
• 21.10 (185) Department Top Three Salaries
• 21.11 (196) Delete Duplicate Emails
• 21.12 (197) Rising Temperature
• 21.13 (262) Trips and Users

#[LeetCode 177] Nth Highest Salary

• 21.3 (177) Nth Highest Salary