LeetCode solutions in Python3.

Table of Contents

• LeetCode
  • Complexity
  • Classical Algorithm
  • Bit Manipulation
  • Array
  • Linked List
  • Stack
  • Recursion
  • Queue
  • Binary Tree
  • Divide and Conquer
  • Hash Table
  • Sort
  • Heap
  • Math
  • Binary Search
  • Binary Search Tree
  • N-ary Tree
  • Graph
  • BackTracking
  • BFS
  • DFS
  • Greedy
  • Design
  • Dynamic Programming
  • SQL Schema
  • 剑指offer
  • 程序员面试经典

Complexity

Time & Space Complexity

Data Structure

Name.	Note
BST	NOTE
Graph	NOTE
Trie	NOTE
Union Find	NOTE
Queue	NOTE

Classical Algorithm

Name.	Note
KMP	NOTE
Recursion	NOTE
Dijkstra	NOTE
Floyd	NOTE
BinarySearch	NOTE
Sort	NOTE
Heap and HeapSort	NOTE
Greedy	NOTE
Dynamic Programming	NOTE
Eight Queue	Backtracking
Hamilton circuit	Backtracking
BFS(unweighted graph shortest path)	NOTE
Tree Traverse	NOTE
Knapsack

Bit Manipulation

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.136	Single Number	Solution	Note	Easy	O(n)	O(1)
No.191	Number of 1 Bits	Solution	Note	Easy	O(1)	O(1)
No.190	Reverse Bits	Solution	Note	Easy	O(1)	O(1)
No.231	Power of Two	Solution	Note	Easy	O(1)	O(1)
No.342	Power of Four	Solution	Note	Easy	O(1)	O(1)
No.401	Binary Watch	Solution	Note	Easy	O(1)	O(1)
No.461	Hamming Distance	Solution	Note	Easy	O(1)	O(1)
No.645	Set Mismatch	Solution	Note	Easy	O(n)	O(1)
No.137	Single NumberII	Solution	Note	Medium	O(n)	O(1)
No.762	Prime Number of Set Bits in Binary Representation	Solution	Note	Medium	O(1)	O(1)
No.371	Sum of Two Integers	Solution	Note	Easy	O(1)	O(1)
No.268	Missing Number	Solution	Note	Easy	O(n)	O(1)	,Math
No.1085	Sum of Digits in the Minimum Number	Solution	Note	Easy	O(n)	O(1)
No.728	Self Dividing Numbers	Solution	Note	Easy	O(nm)	O(1)
No.319	Bulb Switcher	Solution	Note	Medium	O(n)	O(1)
No.201	Bitwise AND of Numbers Range	Solution	Note	Medium	O(1)	O(1)

Two Pointer

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.011	Container With Most Water	Solution	Note	Medium	O(n)	O(1)	two pointer
No.209	Minimum Size Subarray Sum	Solution	Note	Medium	O(n)	O(1)	two pointer
No.083	Remove Duplicates from Sorted List	Solution	Note	Easy	O(n)	O(1)	two pointer
No.922	Sort Array By Parity II	Solution	Note	Easy	O(n)	O(1)	two pointer
No.904	Fruit Into Baskets	Solution	Note	Medium	O(n)	O(1)	two pointer
No.986	Interval List Intersections	Solution	Note	Medium	O(n)	O(1)	two pointer
No.1099	Two Sum Less Than K	Solution	Note	Easy	O(n)	O(1)	two pointer

Array

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.026	Remove Duplicates from Sorted Array	Python C++	Note	Easy	O(n)	O(1)	Array
No.027	Remove Element	Solution	Note	Easy	O(n)	O(1)
No.066	Plus One	Solution	Note	Easy	O(n)	O(1)
No.118	Pascal's Triangle	Solution	Note	Easy	O(n^2)	O(1)
No.119	Pascal's Triangle II	Solution	Note	Easy	O(n^2)	O(1)
No.121	Best Time to Buy and Sell Stock	Solution	Note	Easy	O(n)	O(1)	Array
No.169	Majority Element	Solution	Note	Easy	O(n)	O(1)
No.189	Rotate Array	Solution	Note	Easy	O(n)	O(1)
No.905	Sort Array By Parity	Solution	Note	Easy	O(n)	O(1)
No.896	Monotonic Array	Solution	Note	Easy	O(n)	O(1)
No.243	Shortest Word Distance	Solution	Note	Easy	O(n)	O(1)
No.448	Find All Numbers Disappeared in an Array	Solution	Note	Easy	O(n)	O(1)
No.821	Shortest Distance to a Character	Solution	Note	Easy	O(n)	O(n)
No.001	Two Sum	Solution	Note	Easy	O(n)	O(n)
No.167	Two Sum II	Solution	Note	Easy	O(n)	O(1)
No.170	Two Sum III	Solution	Note	Easy	O(n)	O(1)
No.867	Transpose Matrix	Solution	Note	Easy	O(n)	O(n)
No.860	Lemonade Change	Solution	Note	Easy	O(n)	O(n)
No.849	Maximize Distance to Closest Person	Solution	Note	Easy	O(n)	O(1)
No.840	Magic Squares In Grid	Solution	Note	Easy	O(n)	O(1)
No.283	Move Zeroes	Solution	Note	Easy	O(n)	O(1)
No.015	3sum	Solution	Note	Easy	O(n^2)	O(n)
No.560	Subarray Sum Equals k	Solution	Note	Medium	O(n)	O(1)	prefix sum
No.325	Maximum Size Subarray Sum Equals k	Solution	Note	Medium	O(n)	O(n)	prefix sum
No.930	Binary Subarrays With Sum	Solution	Note	Medium	O(n)	O(n)	prefix sum
No.674	Longest Continuous Increasing Subsequence	Solution	Note	Easy	O(n)	O(1)
No.031	Next Permutation	Solution	Note	Medium	O(nlogn)	O(1)
No.422	Valid Word Square	Solution	Note	Easy	O(n^2)	O(1)
No.349	Intersection of Two Arrays	Solution	Note	Easy	O(n)	O(1)
No.724	Find Pivot Index	Solution	Note	Easy	O(n)	O(1)
No.747	Largest Number At Least Twice of Others	Solution	Note	Easy	O(n)	O(1)
No.498	Diagonal Traverse	Solution	Note	Medium	O(n)	O(n)
No.561	Array Partition I	Solution	Note	Easy	O(nlogn)	O(1)
No.485	Max Consecutive Ones	Solution	Note	Easy	O(n)	O(1)
No.1086	High Five	Solution	Note	Easy	O(n^2logn)	O(n)
No.1064	Fixed Point	Solution	Note	Easy	O(n)	O(n)
No.832	Flipping an Image	Solution	Note	Easy	O(n)	O(n)
No.053	Maximum Subarray	Solution	Note	Easy	O(n)	O(n)	cum sum
No.240	Search a 2D Matrix II	Solution	Note	Easy	O(N+M)	O(1)
No.961	N-Repeated Element in Size 2N Array	Solution	Note	Easy	O(n)	O(n)
No.977	Squares of a Sorted Array	Solution	Note	Easy	O(n)	O(n)
No.016	3Sum Closest	Solution	Note	Medium	O(n^2)	O(1)
No.1207	Unique Number of Occurrences	Solution	Note	Easy	O(n)	O(n)
No.338	Counting Bits	Solution	Note	Medium	O(n)	O(n)
No.259	3sum Smaller	Solution	Note	Medium	O(n^2)	O(1)
No.1007	Minimum Domino Rotations For Equal Row	Solution	Note	Medium	O(n)	O(1)
No.041	First Missing Positive	Solution	Note	Hard	O(n)	O(1)
No.229	Majority Element II	Solution	Note	Hard	O(n)	O(n)
No.923	3Sum With Multiplicity	Solution	Note	Meidum	O(n^2)	O(n)
No.891	Sum of Subsequence Widths	Solution	Note	Hard	O(n^2)	O(n)
No.900	RLE Iterator	Solution	Note	Medium	O(n)	O(n)
No.228	Summary Ranges	Solution	Note	Medium	O(n)	O(n)
No.665	Non-decreasing Array	Solution	Note	Easy	O(n)	O(1)
No.463	Island Perimeter	Solution	Note	Easy	O(n)	O(1)
No.948	Bag of Tokens	Solution	Note	Medium	O(n)	O(1)
No.667	Beautiful Arrangement II	Solution	Note	Medium	O(n)	O(n)
No.419	Battleships in a Board	Solution	Note	Medium	O(nm)	O(1)
No.1014	Best Sightseeing Pair	Solution	Note	Medium	O(n)	O(1)
No.122	Best Time to Buy and Sell Stock II	Solution	Note	Easy	O(n)	O(1)
No.080	Remove Duplicates from Sorted Array II	Solution	Note	Medium	O(n)	O(1)
No.525	Contiguous Array	Solution	Note	Medium	O(n)	O(n)
No.054	Spiral Matrix	Note	Medium	O(n)	O(n)
No.547	Number of Provinces	Note	Medium	O(n^2)	O()	Union Found
No.566	Reshape the Matrix	Note	Medium	O(n^2)	O()
No.073	Set Matrix Zeroes	Note	Medium	O(nm)	O()
No.128	Longest Consecutive Sequence	Note	Medium	O(n)	O(n)
No.043	Multiply Strings	Note	Medium	O(nm)	O(n)
No.048	Rotate Image	Note	Medium	O(nm)	O(nm)

String

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.014	Longest Common Prefix	Solution	Note	Easy	O(n)	O(1)	String
No.028	Implement strStr()	Solution	Note	Easy	O(n + k)	O(1)	kmp
No.038	Count and Say	Solution	Note	Easy	O(n * 2)	O(1)	iteration
No.058	Length of Last Word	Solution	Note	Easy	O(n)	O(1)	count from back
No.067	Add Binary	Solution	Note	Easy	O(n)	O(1)	construction number
No.125	Valid Palindrome	Solution	Note	Easy	O(n)	O(n)
No.165	Compare Version Numbers	Solution	Note	Easy	O(n)	O(n)
No.434	Number of Segments in a String	Solution	Note	Easy	O(n)	O(1)
No.443	String Compression	Solution	Note	Easy	O(n)	O(1)	many pointer
No.459	Repeated Substring Pattern	Solution	Note	Easy	O(n)	O(1)	kmp
No.006	ZigZag Conversion	Solution	Note	Meduim	O(n * k)	O(1)	String
No.521	Longest Uncommon Subsequence I	Solution	Note	Easy	O(n * k)	O(1)	String
No.680	Valid Palindrome II	Solution	Note	Easy	O(n)	O(1)	String
No.681	Next Closest Time	Solution	Note	Medium	O(4^4)	O(1)	DFS
No.771	Jewels and Stones	Solution	Note	Easy	O(n)	O(n)
No.482	License Key Formatting	Solution	Note	Easy	O(n)	O(n)
No.344	Reverse String	Solution	Note	Easy	O(n)	O(1)
No.412	Fizz Buzz	Solution	Note	Easy	O(n)	O(1)
No.005	Longest Palindromic Substring	Solution	Note	Medium	O(n^2)	O(1)
No.819	Most Common Word	Solution	Note	Easy	O(n)	O(n)
No.929	Unique Email Addresses	Solution	Note	Easy	O(n^2)	O(n)
No.535	Encode and Decode TinyURL	Solution	Note	Meduim	O(n)	O(n)
No.271	Encode and Decode Strings	Solution	Note	Meduim	O(n)	O(n)
No.003	Longest Substring Without Repeating Characters	Solution	Note	Meduim	O(n)	O(n)
No.293	Flip Game	Solution	Note	Easy	O(n)	O(n)
No.604	Design Compressed String Iterator	Solution	Note	Easy	O(n)	O(n)	Iterator
No.008	String to Integer (atoi)	Solution	Note	Meduim	O(n)	O(n)
No.151	Reverse Words in a String	Solution	Note	Meduim	O(n)	O(n)
No.557	Reverse Words in a String III	Solution	Note	Easy	O(n)	O(1)
No.1108	Defanging an IP Address	Solution	Note	Easy	O(n)	O(1)
No.1180	Count Substrings with Only One Distinct Letter	Solution	Note	Easy	O(n)	O(1)
No.1134	Armstrong Number	Solution	Note	Easy	O(n)	O(1)
No.709	To Lower Case	Solution	Note	Easy	O(n)	O(1)
No.657	Robot Return to Origin	Solution	Note	Easy	O(n)	O(n)
No.1221	Split a String in Balanced Strings	Solution	Note	Easy	O(n)	O(1)
No.214	Shortest Palindrome	Solution	Note	Hard	O(n^2)	O(n)
No.838	Push Dominoes	Solution	Note	Medium	O(n)	O(n)
No.409	Push Dominoes	Solution	Note	Easy	O(n)	O(n)
No.520	Detect Capital	Solution	Note	Easy	O(1)	O(1)
No.791	Custom Sort String	Solution	Note	Medium	O(n)	O(n)
No.1163	Last Substring in Lexicographical Order	Solution	Note	Hard	O(n^2)	O(1)
No.1790	Check if One String Swap Can Make Strings Equal	Solution	Note	Easy	O(n)	O(1)
No.438	Find All Anagrams in a String	Solution	Note	Medium	O(n)	O(n)
No.383	Ransom Note	Solution	Note	Medium	O(n)	O(n)
No.012	Integer to Roman	Solution	Note	Medium	O(n)	O(n)
No.013	Roman to Integer	Solution	Note	Easy	O(n)	O(n)
No.294	Flip Game II	Solution	Note	Medium	O(n^n)	O(n)
No.157	Read N Characters Given Read4	Solution	Note	Easy	O(n)	O(n)

Linked List

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.021	Merge Two Sorted Lists	Solution	Note	Easy	O(n)	O(1)	guard node
No.024	Swap Nodes in Pairs	Solution	Note	Medium	O(n)	O(1)	watch end
No.160	Intersection of Two Linked Lists	Solution	Note	Easy	O(n)	O(1)
No.203	Remove Linked List Elements	Solution	Note	Easy	O(n)	O(1)
No.237	Delete Node in a Linked List	Solution	Note	Easy	O(1)	O(1)	tricky,del
No.234	Palindrome Linked List	Solution	Note	Meduim	O(1)	O(1)	slow,quick pointer
No.206	Reverse Linked List	Solution	Note	Easy	O(n)	O(1)	reverse
No.002	Add Two Numbers	Solution	Note	Medium	O(n)	O(1)
No.019	Remove Nth Node From End of List	Solution	Note	Medium	O(n)	O(1)	quick slow pointer
No.141	Linked List Cycle	Solution	Note	Easy	O(n)	O(1)	quick slow pointer
No.142	Linked List CycleII	Solution	Note	Medium	O(n)	O(1)	quick slow pointer
No.023	Merge k Sorted Lists	Solution	Note	Hard	O(nlogn)	O(nk)
No.138	Copy List with Random Pointer	Solution	Note	Medium	O(n)	O(n)
No.061	Rotate List	Solution	Note	Medium	O(n)	O(n)
No.082	Remove Duplicates from Sorted List II	Note	Solution	Medium	O(n)	O(n)
No.086	Partition List	Note	Solution	Medium	O(n)	O(n)
No.092	Reverse Linked List II	Note	Solution	Medium	O(n)	O(n)
No.143	Reorder List	Note	Medium	Solution	O(n)	O(n)
No.876	Middle of the Linked List	Note	Solution	Easy	O(n)	O(1)
No.061	Rotate List	Note	Solution	Meduim	O(n)	O(1)

Stack

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.020	Valid Parentheses	Solution	Note	Easy	O(n)	O(1)
No.844	Backspace String Compare	Solution	Note	Easy	O(M+N)	O(1)
No.155	Min Stack	Solution	Note	Easy	O(1)	O(1)
No.173	Binary Search Tree Iterator	Solution	Note	Medium	O(n)	O(1)
No.232	Implement Queue using Stacks	Solution	Note	Easy	O(n)	O(1)
No.682	Baseball Game	Solution	Note	Easy	O(n)	O(1)
No.056	Merge Intervals	Solution	Note	Medium	O(nlogn)	O(n)
No.057	Insert Interval	Solution	Note	Hard	O(n)	O(n)
No.394	Decode String	Solution	Note	Medium	O(n)	O(n)
No.921	Minimum Add to Make Parentheses Valid	Solution	Note	Medium	O(n)	O(n)
No.339	Nested List Weight Sum	Solution	Note	Easy	O(n)	O(1)	DFS
No.716	Max Stack	Solution	Note	Easy	O(n)	O(1)	DFS
No.946	Validate Stack Sequences	Solution	Note	Medium	O(n)	O(n)
No.071	Simplify Path	Solution	Note	Medium	O(n)	O(n)
No.150	Evaluate Reverse Polish Notation	Solution	Note	Medium	O(n)	O(n)
No.225	Implement Stack using Queues	Solution	Note	Easy	O(n)	O(n)
No.341	Flatten Nested List Iterator	Solution	Note	Easy	O(n)	O(n)
No.439	Ternary Expression Parser	Solution	Note	Medium	O(n)	O(n)
No.042	Trapping Rain Water	Solution	Note	Hard	O(n)	O(n)
No.084	Largest Rectangle in Histogram	Solution	Note	Hard	O(n)	O(n)
No.496	Next Greater Element I	Solution	Note	Easy	O(n)	O(n)
No.1021	Remove Outermost Parentheses	Solution	Note	Easy	O(n)	O(n)
No.1081	Smallest Subsequence of Distinct Characters	Solution	Note	Medium	O(n)	O(n)
No.735	Asteroid Collision	Solution	Note	Medium	O(n)	O(n)
No.328	Odd Even Linked List	Solution	Note	Medium	O(n)	O(n)
No.678	Valid Parenthesis String	Solution	Note	Medium	O(n)	O(n)
No.offer09	剑指 Offer 09. 用两个栈实现队列	Solution	Note	Easy	O(n)	O(n)
No.739	Daily Temperatures	Solution	Note	Medium	O(n)	O(n)

Recursion

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.101	Symmetric Tree	Solution	Note	Easy	O(n)	O(h)
No.872	Leaf-Similar Trees	Solution	Note	Easy	O(n)	O(n)
No.104	Maximum Depth of Binary Tree	Solution	Note	Easy	O(logn)	O(1)
No.110	Balanced Binary Tree	Solution	Note	Easy	O(logn)	O(1)
No.111	Minimum Depth of Binary Tree	Solution	Note	Easy	O(logn)	O(1)
No.404	Sum of Left Leaves	Solution	Note	Easy	O(logn)	O(1)
No.669	Trim a Binary Search Tree	Solution	Note	Easy	O(logn)	O(1)
No.671	Second Minimum Node In a Binary Tree	Solution	Note	Easy	O(logn)	O(1)
No.894	All Possible Full Binary Trees	Solution	Note	Easy	O(2^N)	O(n)
No.1137	N-th Tribonacci Number	Solution	Note	Easy	O(n)	O(n)
No.544	Output Contest Matches	Solution	Note	Medium	O(n)	O(n)
No.247	Strobogrammatic Number II	Solution	Note	Medium	O(n)	O(n)
No.721	Accounts Merge	Solution	Note	Medium	O(n^2)	O(n)
No.988	Smallest String Starting From Leaf	Solution	Note	Medium	O(n)	O(n)

Queue

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.346	Moving Average from Data Stream	Solution	Note	Easy	O(1)	O(w)
No.281	Zigzag Iterator	Solution	Note	Medium	O(n)	O(n)
No.127	Word Ladder	Solution	Note	Medium	O(n)	O(n)
No.622	Design Circular Queue	Solution	Note	Medium	O(n)	O(n)
No.641	Design Circular Deque	Solution	Note	Medium	O(n)	O(n)
No.933	Number of Recent Calls	Solution	Note	Easy	O(n)	O(n)

Binary Tree

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.226	Invert Binary Tree	Solution	Note	Easy	O(logn)	O(h)
No.538	Convert BST to Greater Tree	Solution	Note	Easy	O(n)	O(h)
No.543	Diameter of Binary Tree	Solution	Note	Easy	O(n)	O(h)
No.687	Longest Univalue Path	Solution	Note	Easy	O(n)	O(h)
No.897	Increasing Order Search Tree	Solution	Note	Easy	O(n)	O(h)
No.617	Merge Two Binary Trees	Solution	Note	Easy	O(n)	O(h)
No.606	Construct String from Binary Tree	Solution	Note	Easy	O(n)	O(h)
No.572	Subtree of Another Tree	Solution	Note	Easy	O(n)	O(h)
No.563	Binary Tree Tilt	Solution	Note	Easy	O(n^2)
No.094	Binary Tree Inorder Traversal	Solution	Note	Medium	O(n)	O(n)	Inorder Traversal
No.112	Path Sum	Solution	Note	Easy	O(n)	O(1)	DFS
No.257	Binary Tree Paths	Solution	Note	Easy	O(n)	O(1)	DFS
No.144	Binary Tree Preorder Traversal	Solution	Note	Medium	O(n)	O(n)	iteration traverse
No.145	Binary Tree Postorder Traversal	Solution	Note	Hard	O(n)	O(n)	iteration traverse
No.102	Binary Tree Level Order Traversal	Solution	Note	Medium	O(n)	O(n)	iteration traverse
No.250	Count Univalue Subtrees	Solution	Note	Medium	O(n)	O(n)
No.106	Construct Binary Tree from Inorder and Postorder Traversal	Solution	Note	Medium	O(n)	O(n)	build tree
No.105	Construct Binary Tree from Inorder and Preorder Traversal	Solution	Note	Medium	O(n)	O(n)	build tree
No.116	Populating Next Right Pointers in Each Node	Solution	Note	Medium	O(n)	O(n)
No.117	Populating Next Right Pointers in Each Node II	Solution	Note	Medium	O(n)	O(n)
No.236	Lowest Common Ancestor of a Binary Tree	Solution	Note	Medium	O(n^2)	O(n)
No.100	Same Tree	Solution	Note	Medium	O(n)	O(1)
No.314	Binary Tree Vertical Order Traversal	Solution	Note	Medium	O(n)	O(n)
No.637	Average of Levels in Binary Tree	Solution	Note	Easy	O(n)	O(n)
No.103	Binary Tree Zigzag Level Order Traversal	Solution	Note	Medium	O(n)	O(n)
No.114	Flatten Binary Tree to Linked List	Solution	Note	Medium	O(n)	O(1)	DFS
No.437	Path Sum III	Solution	Note	Medium	O(nlogn)	O(1)	DFS
No.965	Univalued Binary Tree	Solution	Note	Easy	O(n)	O(1)
No.1022	Sum of Root To Leaf Binary Numbers	Solution	Note	Easy	O(n)	O(1)
No.993	Cousins in Binary Tree	Solution	Note	Easy	O(n)	O(1)
No.107	Binary Tree Level Order Traversal II	Solution	Note	Easy	O(n)	O(n)
No.654	Maximum Binary Tree	Solution	Note	Medium	O(nlogn)	O(n)
No.1008	Construct Binary Search Tree from Preorder Traversal	Solution	Note	Medium	O(nlogn)	O(n)
No.701	Insert into a Binary Search Tree	Solution	Note	Medium	O(logn)	O(n)
No.814	Binary Tree Pruning	Solution	Note	Medium	O(logn)	O(n)
No.655	Print Binary Tree	Solution	Note	Medium	O(n)	O(n)
No.988	Maximum Binary Tree II	Solution	Note	Medium	O(n)	O(n)
No.1123	Lowest Common Ancestor of Deepest Leaves	Solution	Note	Medium	O(n)	O(n)
No.199	Binary Tree Right Side View	Solution	Note	Medium	O(n)	O(n)
No.1305	All Elements in Two Binary Search Trees	Solution	Note	Medium	O(n)	O(n)
No.1382	Balance a Binary Search Tree	Solution	Note	Medium	O(n)	O(n)
No.1038	Binary Search Tree to Greater Sum Tree	Solution	Note	Medium	O(n)	O(n)
No.652	Find Duplicate Subtrees	Solution	Note	Medium	O(n)	O(n)
No.1261	FFind Elements in a Contaminated Binary Tree	Solution	Note	Medium	O(n)	O(n)
No.124	Binary Tree Maximum Path Sum	Solution	Note	hard	O(n)	O(1)
No.035	Search Insert Position	Solution	Note	hard	O(logn)	O(1)
No.099	Recover Binary Search Tree	Solution	Note	Medium	O(logn)	O(1)
No.156	Binary Tree Upside Down	Solution	Note	Medium	O(logn)	O(1)

Hash Table

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.202	Happy Number	Solution	Note	Easy	O(n)	O(n)
No.204	Count Primes	Solution	Note	Easy	O(n)
No.205	Isomorphic Strings	Solution	Note	Easy	O(n)	O(n)
No.217	Contains Duplicate	Solution	Note	Easy	O(n)	O(n)
No.219	Contains DuplicateII	Solution	Note	Easy	O(n)	O(n)
No.246	Strobogrammatic Number	Solution	Note	Easy	O(n)	O(n)
No.244	Shortest Word Distance II	Solution	Note	Medium	O(m+n)	O(n)
No.249	Group Shifted Strings	Solution	Note	Easy	O(n)	O(n)
No.266	Palindrome Permutation	Solution	Note	Easy	O(n)	O(n)
No.288	Unique Word Abbreviation	Solution	Note	Medium	O(n)	O(n)
No.299	Bulls and Cows	Solution	Note	Medium	O(n)	O(n)
No.387	First Unique Character in a String	Solution	Note	Easy	O(n)	O(n)
No.350	Intersection of Two Arrays II	Solution	Note	Easy	O(n)	O(n)
No.049	Group Anagrams	Solution	Note	Medium	O(nklonk)	O(n)
No.705	Design HashSet	Solution	Note	Easy	O(1)	O(n)
No.599	Minimum Index Sum of Two Lists	Solution	Note	Easy	O(1)	O(n)
No.359	Logger Rate Limiter	Solution	Note	Easy	O(1)	O(n)
No.706	Design HashMap	Solution	Note	Easy	O(1)	O(n)
No.380	Insert Delete GetRandom O(1)	Solution	Note	Medium	O(1)	O(n)
No.981	Time Based Key-Value Store	Solution	Note	Medium	O(nlogn)	O(n)
No.811	Subdomain Visit Count	Solution	Note	Easy	O(nm)	O(n)
No.609	Find Duplicate File in System	Solution	Note	Medium	O(nk)	O(n)
No.692	Top K Frequent Words	Solution	Note	Medium	O(nlogn)	O(n)
No.1119	Remove Vowels from a String	Solution	Note	Easy	O(n)	O(1)
No.1165	Single-Row Keyboard	Solution	Note	Easy	O(n)	O(1)
No.760	Find Anagram Mappings	Solution	Note	Easy	O(n)	O(n)
No.804	Unique Morse Code Words	Solution	Note	Easy	O(n)	O(n)
No.1252	Cells with Odd Values in a Matrix	Solution	Note	Easy	O(n^2)	O(n)
No.954	Array of Doubled Pairs	Solution	Note	Easy	O(n)	O(n)
No.146	LRU Cache	Solution	Note	Medium	O(n)	O(n)

Sort

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.088	Merge Sorted Array	Solution	Note	Medium	O(n+m)	O(1)	three pointer
No.252	Meeting Room	Solution	Note	Easy	O(nlogn)	O(1)
No.075	Sort Colors	Solution	Note	Medium	O(n)	O(1)	tri pointer
No.147	Insertion Sort List	Solution	Note	Medium	O(n^2)	O(1)
No.148	Sort List	Solution	Note	Medium	O(nlog)	O(1)	list merge sort
No.179	Largest Number	Solution	Note	Medium	O(nlogn)	O(1)	cmp_to_key
No.253	Meeting Rooms II	Solution	Note	Medium	O(nlogn)	O(n)
No.347	Top K Frequent Elements	Solution	Note	Medium	O(nlogn)	O(n)
No.581	Shortest Unsorted Continuous Subarray	Solution	Note	Easy	O(n)	O(1)
No.1051	Height Checker	Solution	Note	Easy	O(nlogn)	O(n)
No.207	Course Schedule	Solution	Note	Meduim	O(n)	O(n)
No.912	Sort an Array	Solution	Note	Meduim	O(nlogn)	O(n)
No.406	Queue Reconstruction by Height	Solution	Note	Meduim	O(nlogn)	O(n)

Heap

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.264	Ugly Number II	Solution	Note	Medium	O(n)	O(1)
No.313	Super Ugly Number	Solution	Note	Medium	O(n * k)	O(n * k)
No.378	Kth Smallest Element in a Sorted Matrix	Solution	Note	Medium	O(nklogn)	O(n)
No.215	Kth Largest Element in an Array	Solution	Note	Medium	O(n+klogn)	O(n)
No.937	K Closest Points to Origin	Solution	Note	Medium	O(klogn)	O(n)
No.239	Sliding Window Maximum	Solution	Note	Hard	O(nlogk)	O(n)
No.1046	Last Stone Weight	Solution	Note	Easy	O(nlogn)	O(n)

Binary Search

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.855	Exam Room	Solution	Note	Medium	O(n)	O(n)
No.374	Guess Number Higher or Lower	Solution	Note	Easy	O(logn)	O(1)
No.475	Heaters	Solution	Note	Easy	O(nlogn)	O(1)
No.744	Find Smallest Letter Greater Than Target	Solution	Note	Easy	O(n)	O(1)
No.852	Peak Index in a Mountain Array	Solution	Note	Easy	O(n)	O(1)
No.050	Pow(x, n)	Solution	Note	Medium	O(logn)	O(1)
No.153	Find Minimum in Rotated Sorted Array	Solution	Note	Medium	O(logn)	O(n)
No.704	Binary Search	Solution	Note	Easy	O(logn)	O(1)
No.1201	Ugly Number III	Solution	Note	Medium	O(logn)	O(1)
No.074	Search a 2D Matrix	Solution	Note	Medium	O(logn)	O(1)
No.162	Find Peak Element	Solution	Note	Medium	O(logn)	O(1)

Binary Search Tree

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.235	Lowest Common Ancestor of a Binary Search Tree	Solution	Note	Easy	O(logn)	O(1)
No.270	Closest Binary Search Tree Value	Solution	Note	Easy	O(logn)	O(1)
No.653	Two Sum IV - Input is a BST	Solution	Note	Easy	O(n)	O(n)
No.098	Validate Binary Search Tree	Solution	Note	Easy	O(n)	O(n)
No.278	First Bad Version	Solution	Note	Easy	O(logn)	O(1)
No.033	Search in Rotated Array	Solution	Note	Medium	O(logn)	O(1)
No.173	Binary Search Tree Iterator	Solution	Note	Medium	O(1)	O(h)
No.938	Range Sum of BST	Solution	Note	Easy	O(n)	O(1)
No.700	Search in a Binary Search Tree	Solution	Note	Easy	O(n)	O(1)
No.108	Convert Sorted Array to Binary Search Tree	Solution	Note	Easy	O(n)	O(1)
No.530	Minimum Absolute Difference in BST	Solution	Note	Easy	O(n)	O(1)
No.783	Minimum Distance Between BST Nodes	Solution	Note	Easy	O(n)	O(1)
No.501	Find Mode in Binary Search Tree	Solution	Note	Easy	O(n)	O(n)
No.776	Split BST	Solution	Note	Medium	O(logn)	O(n)
No.426	Convert Binary Search Tree to Sorted Doubly Linked List	Solution	Note	Medium	O(n)	O(1)
No.230	Kth Smallest Element in a BST	Solution	Note	Medium	O(n)	O(1)

N-ary Tree

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.589	N-ary Tree Preorder Traversal	Solution	Note	Easy	O(n)	O(n)
No.590	N-ary Tree Postorder Traversal	Solution	Note	Easy	O(n)	O(n)
No.429	N-ary Tree Levelorder Traversal	Solution	Note	Easy	O(n)	O(n)
No.559	Maximum Depth of N-ary Tree	Solution	Note	Easy	O(n)	O(n)
No.208	Implement Trie (Prefix Tree)	Solution	Note	Medium	O(k)	O(n)	trie
No.677	Map Sum Pairs	Solution	Note	Medium			trie
No.648	Replace Words	Solution	Note	Medium	O(n)	O(n)	trie
No.211	Add and Search Word - Data structure design	Solution	Note	Medium	O(n)	O(n)	trie
No.1233	Remove Sub-Folders from the Filesystem	Solution	Note	Medium	O(n)	O(n)	trie
No.720	Longest Word in Dictionary	Solution	Note	Easy	O(n^2)	O(n)	trie

Math

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.263	Ugly Number	Solution	Note	Easy	O(n)	O(1)
No.238	Product of Array Except Self	Solution	Note	Medium	O(n)	O(n)
No.621	Task Scheduler	Solution	Note	Medium	O(n)	O(1)
No.326	Power of Three	Solution	Note	Easy	O(n)	O(1)
No.892	Surface Area of 3D Shapes	Solution	Note	Easy	O(n)	O(1)
No.1266	Minimum Time Visiting All Points	Solution	Note	Easy	O(n)	O(1)
No.1281	Subtract the Product and Sum of Digits of an Integer	Solution	Note	Easy	O(n)	O(n)
No.1232	Check If It Is a Straight Line	Solution	Note	Easy	O(n)	O(1)
No.258	Add Digits	Solution	Note	Easy	O(n)	O(n)
No.069	Sqrt(x)	Solution	Note	Easy	O(n)	O(1)
No.1033	Moving Stones Until Consecutive	Solution	Note	Easy	O(1)	O(1)
No.1342	Number of Steps to Reduce a Number to Zero	Solution	Note	Easy	O(n)	O(1)
No.504	Base 7	Solution	Note	Easy	O(n)	O(1)
No.470	Implement Rand10() Using Rand7()	Solution	Note	medium	O(1)	O(1)
No.154	Find Minimum in Rotated Sorted Array II	Solution	Note	hard	O(n)	O(1)
No.007	Reverse Integer	Solution	Note	Medium	O(1)	O(1)

Graph

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag

Backtracking

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.017	Letter Combinations of a Phone Number	Solution	Note	Medium	O(n)	O(n)
No.093	Restore IP Addresses	Solution	Note	Medium	O(n^4)	O(n)
No.078	Subset	Solution	Note	Medium	O(2^n)	O(n)
No.078	SubsetII	Solution	Note	Medium	O(2^n)	O(n)
No.046	Permutations	Solution	Note	Medium	O(n!)	O(n)
No.047	PermutationsII	Solution	Note	Medium	O(n!)	O(n)
No.079	Word Search	Solution	Note	Medium	O(n^2)	O(n)
No.022	Generate Parentheses	Solution	Note	Medium	O(n!)	O(n)
No.039	Combination Sum	Solution	Note	Medium	O(n!)	O(n)
No.784	Letter Case Permutation	Solution	Note	Easy	O(n*2)	O(n) + O(n*2)
No.1079	Letter Tile Possibilities	Solution	Note	Easy	O(2*n)	O(2*n)
No.077	Combinations	Solution	Note	Medium	O(2^n)	O(2^n)
No.040	Combination Sum II	Solution	Note	Medium	O(n^n)	O(n^n)
No.695	Max Area of Island	Solution	Note	Medium	O(n^2)	O(n^2)

BFS

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.200	Number of Islands	Solution	Note	Medium	O(n)	O(n)	BFS
No.133	Clone Graph	Solution	Note	Medium	O(n)	O(n)	BFS
No.1162	As Far from Land as Possible	Solution	Note	Medium	O(n)	O(n)	BFS

DFS

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.1145	Binary Tree Coloring Game	Solution	Note	Medium	O(n)	O(1)
No.863	All Nodes Distance K in Binary Tree	Solution	Note	Medium	O(n)	O(n)
No.1034	Coloring A Border	Solution	Note	Medium	O(n)	O(n)
No.306	Additive Number	Solution	Note	Medium	O(n^2)	O(n)
No.842	Split Array into Fibonacci Sequence	Solution	Note	Medium	O(n^2)	O(n)
No.399	Evaluate Division	Solution	Note	Medium	O(n)	O(n)	DFS
No.526	Beautiful Arrangement	Solution	Note	Medium	O(n!)	O(n)	DFS
No.733	Flood Fill	Solution	Note	Easy	O(n^2)	O(1)

Greedy

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.455	Assign Cookies	Solution	Note	Easy	O(nlogn)	O(1)
No.055	Jump Game	Solution	Note	Medium	O(n)	O(1)
No.2086	Minimum Number of Buckets Required to Collect Rainwater from Houses	Solution	Note	Medium	O(n)	O(1)

Divide and Conquer

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.932	Beautiful Array	Solution	Note	Medium	O(nlogn)	O(n)
No.241	Different Ways to Add Parentheses	Solution	Note	Medium	O(nlogn)	O(n)

Dynamic Programming

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.091	Decode Ways	Solution	Note	Medium	O(n)	O(1)
No.062	Unique Paths	Solution	Note	Medium	O(n^2)	O(n)
No.070	Combing Stairs	Solution	Note	Medium	O(n)	O(n)
No.926	Flip String to Monotone Increasing	Solution	Note	Medium	O(n)	O(n)
No.845	Longest Mountain in Array	Solution	Note	Medium	O(n)	O(1)
No.139	Longest Mountain in Array	Solution	Note	Medium	O(n)	O(1)
No.300	Longest Increasing Subsequence	Solution	Note	Medium	O(nlogn)	O(1)
No.198	House Robber	Solution	Note	Easy	O(n)	O(n)
No.213	House Robber II	Solution	Note	Medium	O(n)	O(n)
No.746	Min Cost Climbing Stairs	Solution	Note	Easy	O(n)	O(n)
No.790	Domino and Tromino Tiling	Solution	Note	Medium	O(n)	O(n)
No.801	Minimum Swaps To Make Sequences Increasing	Solution	Note	Medium	O(n)	O(n)
No.718	Maximum Length of Repeated Subarray	Solution	Note	Medium	O(n*m)	O(n*m)
No.1143	Longest Common Subsequence	Solution	Note	Medium	O(n*m)	O(n*m)
No.583	Delete Operation for Two Strings	Solution	Note	Medium	O(n*m)	O(n*m)
No.1092	Shortest Common Supersequence	Solution	Note	Hard	O(n*m)	O(n*m)
No.032	Longest Valid Parentheses	Solution	Note	Hard	O(n)	O(n)
No.152	Maximum Product Subarray	Solution	Note	Medium	O(n)	O(1)
No.647	Palindromic Substrings	Solution	Note	Medium	O(n^2)	O(1)
No.416	Partition Equal Subset Sum	Solution	Note	Medium	O(n^2)	O(n)
No.279	Perfect Squares	Solution	Note	Medium	O(n^2)	O(n)
No.418	Sentence Screen Fitting	Solution	Note	Medium	O(n^2)	O(n)
No.070	Climbing Stairs	Solution	Note	Medium	O(n)	O(n)
No.6305	Climbing Stairs	Solution	Note	Medium	O(n)	O(1)
No.322	Coin Change	Solution	Note	Medium	O(n)	O(1)
No.064	Minimum Path Sum	Solution	Note	Medium	O(n*m)	O(m*n)
No.343	Integer Break	Solution	Note	Medium	O(n^2)	O(n)

Design

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.1063	Design Parking System	Solution	Note	Easy	O(n)	O(1)

SQL Schema

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.1068	Product Sales Analysis I	Solution	Note	Easy	O(n*n)	O(n*n)
No.1069	Product Sales Analysis II	Solution	Note	Easy	O(n)	O(n)
No.511	Game Play Analysis I	Solution	Note	Easy	O(n)	O(n)
No.595	Big Countries	Solution	Note	Easy	O(n)	O(n)
No.1173	Immediate Food Delivery I	Solution	Note	Easy	O(n)	O(n)
No.613	Shortest Distance in a Line	Solution	Note	Easy	O(n)	O(n)
No.1050	Actors and Directors Who Cooperated At Least Three Times	Solution	Note	Easy	O(n)	O(n)
No.627	Swap Salary	Solution	Note	Easy	O(n)	O(1)
No.1082	Sales Analysis I	Solution	Note	Easy	O(n)	O(1)
No.620	Not Boring Movies	Solution	Note	Easy	O(n)	O(1)

剑指offer

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.LZOF_03	数组中重复的数字	Solution	Note	Easy	O(n)	O(1)
No.LZOF_04	二维数组中的查找	Solution	Note	Easy	O(nlogn)	O(1)
No.LZOF_05	替换空格	Solution	Note	Easy	O(n)	O(n)
No.LZOF_06	从尾到头打印链表	Solution	Note	Easy	O(n)	O(n)
No.LZOF_07	重建二叉树	Solution	Note	Medium	O(n)	O(n)
No.LZOF_09	用两个栈实现队列	Solution	Note	Easy	O(n)	O(n)
No.LZOF_10	斐波那契数列	Solution	Note	Easy	O(n)	O(n)
No.LZOF_10-2	青蛙跳台阶问题	Solution	Note	Easy	O(n)	O(n)
No.LZOF_11	旋转数组的最小数字	Solution	Note	Easy	O(n)	O(1)
No.LZOF_12	矩阵中的路径	Solution	Note	Medium	O(n*2)	O(n)
No.LZOF_13	机器人的运动范围	Solution	Note	Medium	O(n*2)	O(n)
No.LZOF_14	剪绳子	Solution	Note	Medium	O(n*2)	O(n)
No.LZOF_14_II	剪绳子II	Solution	Note	Medium	O(n*2)	O(n)
No.LZOF_15	二进制中1的个数	Solution	Note	Medium	O(n)	O(1)
No.LZOF_16	数值的整数次方	Solution	Note	Medium	O(logn)	O(1)
No.LZOF_17	打印从1到最大的n位数	Solution	Note	Easy	O(n)	O(n)
No.LZOF_18	删除链表的节点	Solution	Note	Easy	O(n)	O(n)
No.LZOF_19	正则表达式匹配	Solution	Note	Hard	O(nm)	O(nm)
No.LZOF_21	调整数组顺序使奇数位于偶数前面	Solution	Note	Easy	O(n)	O(1)
No.LZOF_22	链表中倒数第k个节点	Solution	Note	Easy	O(n)	O(1)
No.LZOF_24	反转链表	Solution	Note	Easy	O(n)	O(1)
No.LZOF_25	合并两个排序的链表	Solution	Note	Easy	O(n)	O(1)
No.LZOF_26	树的子结构	Solution	Note	Easy	O(n^2)	O(1)
No.LZOF_27	二叉树的镜像	Solution	Note	Easy	O(n)	O(1)
No.LZOF_28	对称的二叉树	Solution	Note	Easy	O(n)	O(1)
No.LZOF_29	顺时针打印矩阵	Solution	Note	Easy	O(n)	O(n)
No.LZOF_30	包含min函数的栈	Solution	Note	Easy	O(1)	O(1)
No.LZOF_31	栈的压入、弹出序列	Solution	Note	Medium	O(n)	O(n)
No.LZOF_32	从上到下打印二叉树	Solution	Note	Medium	O(n)	O(n)
No.LZOF_32_II	从上到下打印二叉树 II	Solution	Note	Medium	O(n)	O(n)
No.LZOF_32_III	从上到下打印二叉树 III	Solution	Note	Medium	O(n)	O(n)
No.LZOF_33	二叉搜索树的后序遍历序列	Solution	Note	Medium	O(n)	O(n)
No.LZOF_34	二叉树中和为某一值的路径	Solution	Note	Medium	O(n)	O(n)
No.LZOF_35	复杂链表的复制	Solution	Note	Medium	O(n)	O(n)
No.LZOF_36	二叉搜索树与双向链表	Solution	Note	Medium	O(n)	O(1)
No.LZOF_37	序列化二叉树	Solution	Note	Hard	O(n)	O(n)
No.LZOF_38	字符串的排列	Solution	Note	Medium	O(n!)	O(n)
No.LZOF_39	数组中出现次数超过一半的数字	Solution	Note	Easy	O(nlogn)	O(1)
No.LZOF_40	最小的k个数	Solution	Note	Easy	O(nlogk)	O(1)
No.LZOF_41	连续子数组的最大和	Solution	Note	Easy	O(n)	O(1)
No.LZOF_49	丑数	Solution	Note	Medium	O(n)	O(1)
No.LZOF_48	最长不含重复字符的子字符串	Solution	Note	Medium	O(n)	O(n)
No.LZOF_47	礼物的最大价值	Solution	Note	Medium	O(n)	O(n*2)
No.LZOF_46	把数字翻译成字符串	Solution	Note	Medium	O(n*2)	O(1)
No.LZOF_45	把数组排成最小的数	Solution	Note	Medium	O(nlogn)	O(n)
No.LZOF_50	第一个只出现一次的字符	Solution	Note	Easy	O(n)	O(n)
No.LZOF_52	两个链表的第一个公共节点	Solution	Note	Easy	O(n)	O(1)
No.LZOF_53_I	在排序数组中查找数字I	Solution	Note	Easy	O(logn)	O(1)
No.LZOF_53_II	0～n-1中缺失的数字	Solution	Note	Easy	O(n)	O(1)
No.LZOF_54	二叉搜索树的第k大节点	Solution	Note	Easy	O(nlogk)	O(n)
No.LZOF_55_I	二叉树的深度	Solution	Note	Easy	O(n)	O(1)
No.LZOF_55_II	平衡二叉树	Solution	Note	Easy	O(n)	O(1)
No.LZOF_56_I	数组中数字出现的次数	Solution	Note	medium	O(n)	O(1)
No.LZOF_57	和为s的两个数字	Solution	Note	Easy	O(n)	O(1)
No.LZOF_57_II	和为s的连续正数序列	Solution	Note	Easy	O(n)	O(n)
No.LZOF_58_I	翻转单词顺序	Solution	Note	Easy	O(n)	O(1)
No.LZOF_58_II	左旋转字符串	Solution	Note	Easy	O(n)	O(1)
No.LZOF_59_I	滑动窗口的最大值	Solution	Note	Easy	O(n)	O(N)
No.LZOF_59_II	队列的最大值	Solution	Note	Medium	O(1)	O(N)
No.LZOF_68_I	二叉搜索树的最近公共祖先	Solution	Note	Easy	O(n)	O(n)
No.LZOF_68_II	二叉树的最近公共祖先	Solution	Note	Medium	O(n)	O(n)
No.LZOF_67	把字符串转换成整数	Solution	Note	Easy	O(n)	O(n)
No.LZOF_66	构建乘积数组	Solution	Note	Easy	O(n)	O(n)
No.LZOF_65	不用加减乘除做加法	Solution	Note	Easy	O(n)	O(n)
No.LZOF_63	股票的最大利润	Solution	Note	Medium	O(n)	O(1)
No.LZOF_65	n个骰子的点数	Solution	Note	Easy	O(n)	O(1)
No.LZOF_62	圆圈中最后剩下的数字	Solution	Note	Easy	O(n)	O(n)
No.LZOF_61	扑克牌中的顺子	Solution	Note	Easy	O(n)	O(n)
No.LZOF_64	求1+2+...+n	Solution	Note	Medium	O(n)	O(n)
No.LZOF_56_II	数组中数字出现的次数 II	Solution	Note	Medium	O(n)	O(1)
No.LZOF41	数据流中的中位数	Solution	Note	Hard	O(n^2)	O(n)

程序员面试经典

NO.	Title	Solution	Note	Difficulty	Time	Space	Tag
No.CXY_01_01	判定字符是否唯一	Solution	Note	Easy	O(n)	O(n)
No.CXY_01_02	判定是否互为字符重排	Solution	Note	Easy	O(n)	O(n)
No.CXY_01_03	URL化	Solution	Note	Easy	O(n)	O(1)
No.CXY_01_04	回文排列	Solution	Note	Easy	O(n)	O(n)
No.CXY_01_05	一次编辑	Solution	Note	Medium	O(n)	O(1)
No.CXY_01_06	字符串压缩	Solution	Note	Easy	O(n)	O(n)
No.CXY_01_07	旋转矩阵	Solution	Note	Medium	O(n)	O(1)
No.CXY_01_08	零矩阵	Solution	Note	Medium	O(n^2)	O(1)
No.CXY_01_09	字符串轮转	Solution	Note	Easy	O(s1+s2)	O(n)
No.CXY_02_01	移除重复节点	Solution	Note	Easy	O(n)	O(n)
No.CXY_02_02	返回倒数第 k 个节点	Solution	Note	Easy	O(n)	O(n)
No.CXY_02_03	删除中间节点	Solution	Note	Easy	O(1)	O(1)
No.CXY_02_04	分割链表	Solution	Note	Medium	O(n)	O(1)
No.CXY_02_05	链表求和	Solution	Note	Medium	O(n)	O(n)
No.CXY_02_06	回文链表	Solution	Note	Medium	O(n)	O(1)
No.CXY_02_07	链表相交	Solution	Note	Easy	O(n)	O(1)
No.CXY_02_08	环路检测	Solution	Note	Easy	O(n)	O(1)
No.CXY_03_01	三合一	Solution	Note	Easy	O(n)	O(n)
No.CXY_03_02	栈的最小值	Solution	Note	Easy	O(n)	O(1)
No.CXY_03_03	堆盘子	Solution	Note	Medium	O(n)	O(n)
No.CXY_03_04	化栈为队	Solution	Note	Easy	O(n)	O(n)
No.CXY_03_05	栈排序	Solution	Note	Medium	O(n)	O(n)
No.CXY_03_06	动物收容所	Solution	Note	Easy	O(n)	O(n)
No.CXY_04_01	节点间通路	Solution	Note	Medium	O(n)	O(n)
No.CXY_04_02	最小高度树	Solution	Note	Easy	O(n)	O(n)
No.CXY_04_03	特定深度节点链表	Solution	Note	Medium	O(n)	O(n)
No.CXY_04_04	检查平衡性	Solution	Note	Easy	O(n)	O(n)
No.CXY_04_05	合法二叉搜索树	Solution	Note	Medium	O(n)	O(n)
No.CXY_04_06	后继者	Solution	Note	Medium	O(n)	O(n)
No.CXY_04_08	首个共同祖先	Solution	Note	Medium	O(n)	O(n)
No.CXY_04_10	检查子树	Solution	Note	Medium	O(n^2)	O(n)
No.CXY_04_12	求和路径	Solution	Note	Medium	O(n)	O(n)
No.CXY_08_01	三步问题	Solution	Note	Easy	O(n)	O(n)
No.CXY_08_02	迷路的机器人	Solution	Note	Medium	O(100^2)	O(n)
No.CXY_08_03	魔术索引	Solution	Note	Easy	O(n)	O(1)
No.CXY_08_04	幂集	Solution	Note	Medium	O(n^2)	O(n)
No.CXY_08_05	递归乘法	Solution	Note	Medium	O(n)	O(n)
No.CXY_08_06	汉诺塔问题	Solution	Note	Easy	O(2^n)	O(n)