leetcode问题分析：总述

前言：

　　最近在学着做leetcode上面所有的习题。这里列举出了很多公司面试的问题，撇开功利的目的，对这些问题的研究对于学习总结也有很重要的意义。于是想尝试一下把自己解决问题的思路以及详细的解答都记录下来。在以前的学习中，经常碰到一些比较困难的问题去搜索答案的时候，看到的只是贴的一大堆代码。也许结果是对的，可是没有描述为什么会有这样的结果，这个结果是怎么来的。于是如果问题有一些变化，还是不知道该怎么做。所以问题的核心还是在于它的本质以及背后的思想。

　　本文是所有问题以及其解答的一个索引。引用一下本人微博上的一句话：只贴代码不讲思路的其行为比看帖不回帖更可恶 :)

 

问题列表

问题	解答分析
Two Sum	分析解答
Median of Two Sorted Arrays	分析解答
Longest Substring Without Repeating Characters	分析解答
Add Two Numbers	分析解答
Longest Palindromic Substring	分析解答
ZigZag Conversion	分析解答
Reverse Integer	分析解答
String to Integer (atoi)	分析解答
Palindrome Number	分析解答
Regular Expression Matching	分析解答
Container With Most Water	分析解答
Integer to Roman	分析解答
Roman to Integer	分析解答
Longest Common Prefix	分析解答
3Sum	分析解答
3Sum Closest	分析解答
4Sum	分析解答
Letter Combinations of a Phone Number	分析解答
Remove Nth Node From End of List	分析解答
Valid Parentheses	分析解答
Generate Parentheses	分析解答
Merge k Sorted Lists	分析解答
Swap Nodes in Pairs	分析解答
Reverse Nodes in k-Group	分析解答
Remove Duplicates from Sorted Array	分析解答
Remove Element	分析解答
Implement strStr()	分析解答
Divide Two Integers	分析解答
Substring with Concatenation of All Words	分析解答
Next Permutation	分析解答
Longest Valid Parentheses	分析解答
Search in Rotated Sorted Array	分析解答
Search for a Range	分析解答
Search Insert Position	分析解答
Valid Sudoku	分析解答
Sudoku Solver	分析解答
Count and Say	分析解答
Combination Sum	分析解答
Combination Sum II	分析解答
First Missing Positive	分析解答
Trapping Rain Water	分析解答
Multiply Strings	分析解答
Wildcard Matching	分析解答
Jump Game II	分析解答
Permutations	分析解答
Permutations II	分析解答
Rotate Image	分析解答
Group Anagrams	分析解答
Pow(x, n)	分析解答
N-Queens	分析解答
N-Queens II	分析解答
Maximum Subarray	分析解答
Spiral Matrix	分析解答
Jump Game	分析解答
Merge Intervals	分析解答
Insert Interval	分析解答
Length of Last Word	分析解答
Spiral Matrix II	分析解答
Permutation Sequence	分析解答
Rotate List	分析解答
Unique Paths	分析解答
Unique Paths II	分析解答
Minimum Path Sum	分析解答
Merge Two Sorted Lists	分析解答
Add Binary	分析解答
Valid Number	分析解答
Plus One	分析解答
Text Justification	分析解答
Sqrt(x)	分析解答
Climbing Stairs	分析解答
Simplify Path	分析解答
Edit Distance	分析解答
Set Matrix Zeroes	分析解答
Search a 2D Matrix	分析解答
Sort Colors	分析解答
Minimum Window Substring	分析解答
Combinations	分析解答
Subsets	分析解答
Word Search	分析解答
Remove Duplicates from Sorted Array II	分析解答
Search in Rotated Sorted Array II	分析解答
Remove Duplicates from Sorted List	分析解答
Remove Duplicates from Sorted List II	分析解答
Largest Rectangle in Histogram	分析解答
Maximal Rectangle	分析解答
Partition List	分析解答
Scramble String	分析解答
Merge Sorted Array	分析解答
Gray Code	分析解答
Decode Ways	分析解答
Subsets II	分析解答
Reverse Linked List II	分析解答
Restore IP Addresses	分析解答
Binary Tree Inorder Traversal	分析解答
Unique Binary Search Trees	分析解答
Unique Binary Search Trees II	分析解答
Interleaving String	分析解答
Validate Binary Search Tree	分析解答
Recover Binary Search Tree	分析解答
Same Tree	分析解答
Symmetric Tree	分析解答
Binary Tree Level Order Traversal	分析解答
Binary Tree Zigzag Level Order Traversal	分析解答
Maximum Depth of Binary Tree	分析解答
Construct Binary Tree from Preorder and Inorder Traversal	分析解答
Construct Binary Tree from Inorder and Postorder Traversal	分析解答
Binary Tree Level Order Traversal II	分析解答
Convert Sorted Array to Binary Search Tree	分析解答
Convert Sorted List to Binary Search Tree	分析解答
Balanced Binary Tree	分析解答
Minimum Depth of Binary Tree	分析解答
Path Sum	分析解答
Path Sum II	分析解答
Flatten Binary Tree to Linked List	分析解答
Distinct Subsequences	分析解答
Populating Next Right Pointers in Each Node	分析解答
Populating Next Right Pointers in Each Node II	分析解答
Pascal's Triangle	分析解答
Pascal's Triangle II	分析解答
Triangle	分析解答
Best Time to Buy and Sell Stock	分析解答
Best Time to Buy and Sell Stock II	分析解答
Best Time to Buy and Sell Stock III	分析解答
Binary Tree Maximum Path Sum	分析解答
Valid Palindrome	分析解答
Word Ladder	分析解答
Word Ladder II
Longest Consecutive Sequence	分析解答
Sum Root to Leaf Numbers	分析解答
Surrounded Regions	分析解答
Palindrome Partitioning	分析解答
Palindrome Partitioning II	分析解答
Clone Graph	分析解答
Gas Station	分析解答
Candy	分析解答
Single Number	分析解答
Single Number II	分析解答
Copy List with Random Pointer	分析解答
Word Break	分析解答
Word Break II	分析解答
Linked List Cycle	分析解答
Linked List Cycle II	分析解答
Reorder List	分析解答
Binary Tree Preorder Traversal	分析解答
Binary Tree Postorder Traversal	分析解答
LRU Cache	分析解答
Insertion Sort List	分析解答
Sort List	分析解答
Max Points on a Line	分析解答
Evaluate Reverse Polish Notation	分析解答
Reverse Words in a String	分析解答
Maximum Product Subarray	分析解答
Find Minimum in Rotated Sorted Array	分析解答
Find Minimum in Rotated Sorted Array II	分析解答
Min Stack	分析解答
Binary Tree Upside Down	分析解答
Read N Characters Given Read4
Read N Characters Given Read4 II - Call multiple times
Longest Substring with At Most Two Distinct Characters
Intersection of Two Linked Lists
One Edit Distance
Find Peak Element
Missing Ranges
Maximum Gap
Compare Version Numbers
Fraction to Recurring Decimal
Two Sum II - Input array is sorted
Excel Sheet Column Title
Majority Element
Two Sum III - Data structure design
Excel Sheet Column Number
Factorial Trailing Zeroes
Binary Search Tree Iterator
Dungeon Game
Largest Number
Reverse Words in a String II
Repeated DNA Sequences
Best Time to Buy and Sell Stock IV
Rotate Array
Reverse Bits
Number of 1 Bits
House Robber
Binary Tree Right Side View
Number of Islands
Bitwise AND of Numbers Range
Happy Number
Remove Linked List Elements
Count Primes
Isomorphic Strings
Reverse Linked List
Course Schedule
Implement Trie (Prefix Tree)
Minimum Size Subarray Sum
Course Schedule II
Add and Search Word - Data structure design
Word Search II
House Robber II
Shortest Palindrome
Kth Largest Element in an Array
Combination Sum III
Contains Duplicate
The Skyline Problem
Contains Duplicate II
Contains Duplicate III
Maximal Square
Count Complete Tree Nodes
Rectangle Area
Basic Calculator
Implement Stack using Queues
Invert Binary Tree
Basic Calculator II
Summary Ranges
Majority Element II
Kth Smallest Element in a BST
Power of Two
Implement Queue using Stacks
Number of Digit One	分析解答
Palindrome Linked List
Lowest Common Ancestor of a Binary Search Tree	分析解答
Lowest Common Ancestor of a Binary Tree	分析解答
Delete Node in a Linked List
Product of Array Except Self
Sliding Window Maximum
Search a 2D Matrix II
Different Ways to Add Parentheses
Valid Anagram
Shortest Word Distance
Shortest Word Distance II
Shortest Word Distance III
Strobogrammatic Number
Strobogrammatic Number II
Strobogrammatic Number III
Group Shifted Strings
Count Univalue Subtrees
Flatten 2D Vector
Meeting Rooms
Meeting Rooms II
Factor Combinations
Verify Preorder Sequence in Binary Search Tree
Paint House
Binary Tree Paths
Add Digits
3Sum Smaller
Single Number III
Graph Valid Tree
Ugly Number
Ugly Number II
Paint House II
Palindrome Permutation
Palindrome Permutation II
Missing Number
Alien Dictionary
Closest Binary Search Tree Value
Encode and Decode Strings
Closest Binary Search Tree Value II
Integer to English Words
H-Index
H-Index II
Paint Fence
Find the Celebrity
First Bad Version
Perfect Squares
Wiggle Sort
Zigzag Iterator
Expression Add Operators
Move Zeroes
Peeking Iterator
Inorder Successor in BST
Walls and Gates
Find the Duplicate Number
Unique Word Abbreviation
Game of Life
Word Pattern
Word Pattern II
Nim Game
Flip Game
Flip Game II
Find Median from Data Stream
Best Meeting Point
Serialize and Deserialize Binary Tree
Binary Tree Longest Consecutive Sequence
Bulls and Cows
Longest Increasing Subsequence
Remove Invalid Parentheses
Smallest Rectangle Enclosing Black Pixels
Range Sum Query - Immutable
Range Sum Query 2D - Immutable
Number of Islands II
Additive Number
Range Sum Query - Mutable
Range Sum Query 2D - Mutable
Best Time to Buy and Sell Stock with Cooldown
Minimum Height Trees
Sparse Matrix Multiplication
Burst Balloons
Super Ugly Number
Binary Tree Vertical Order Traversal
Count of Smaller Numbers After Self
Remove Duplicate Letters
Shortest Distance from All Buildings
Maximum Product of Word Lengths
Bulb Switcher
Generalized Abbreviation
Create Maximum Number
Coin Change
Number of Connected Components in an Undirected Graph
Wiggle Sort II
Maximum Size Subarray Sum Equals k
Power of Three
Count of Range Sum
Odd Even Linked List
Longest Increasing Path in a Matrix
Patching Array
Verify Preorder Serialization of a Binary Tree
Reconstruct Itinerary
Largest BST Subtree
Increasing Triplet Subsequence
Self Crossing
Palindrome Pairs
House Robber III
Counting Bits
Nested List Weight Sum
Longest Substring with At Most K Distinct Characters
Flatten Nested List Iterator
Power of Four
Integer Break
Reverse String
Reverse Vowels of a String
Moving Average from Data Stream
Top K Frequent Elements
Design Tic-Tac-Toe
Intersection of Two Arrays
Intersection of Two Arrays II
Android Unlock Patterns
Data Stream as Disjoint Intervals
Design Snake Game
Russian Doll Envelopes
Line Reflection
Count Numbers with Unique Digits
Rearrange String k Distance Apart
Logger Rate Limiter
Sort Transformed Array
Bomb Enemy
Design Hit Counter
Max Sum of Rectangle No Larger Than K
Nested List Weight Sum II
Water and Jug Problem
Find Leaves of Binary Tree
Valid Perfect Square
Largest Divisible Subset
Plus One Linked List
Range Addition
Sum of Two Integers
Super Pow
Find K Pairs with Smallest Sums
Guess Number Higher or Lower
Guess Number Higher or Lower II
Wiggle Subsequence
Combination Sum IV
Kth Smallest Element in a Sorted Matrix
Design Phone Directory
Insert Delete GetRandom O(1)
Insert Delete GetRandom O(1) - Duplicates allowed
Linked List Random Node
Ransom Note
Shuffle an Array
Mini Parser
Lexicographical Numbers
First Unique Character in a String
Longest Absolute File Path
Find the Difference
Perfect Rectangle
Is Subsequence
UTF-8 Validation
Decode String
Longest Substring with At Least K Repeating Characters
Rotate Function
Integer Replacement
Random Pick Index
Evaluate Division
Nth Digit
Binary Watch
Remove K Digits
Frog Jump
Sum of Left Leaves
Convert a Number to Hexadecimal
Queue Reconstruction by Height
Trapping Rain Water II
Valid Word Abbreviation
Longest Palindrome
Split Array Largest Sum