Problem List (245)

Leet Code

#	Title	Solution	Difficulty
1898	Maximum Number of Removable Characters	Binary Search	Medium
1893	Check if All the Integers in a Range Are Covered	Different Array Prefix Sum Hash Table	Simple
1877	Minimize Maximum Pair Sum in Array	Sort Two Pointers	Medium
1846	Maximum Element After Decreasing and Rearranging	Array Sort	Medium
1838	Frequency of the Most Frequent Element	Sliding Window	Medium
1818	Minimum Absolute Sum Difference	Array Binary Search	Medium
1337	The K Weakest Rows in a Matrix	Binary Search Heap	Simple
1104	Path In Zigzag Labelled Binary Tree	Array Binary Tree	Medium
987	Vertical Order Traversal of a Binary Tree	Sort Tree Traversal	Hard
981	Time Based Key-Value Store	Hash Table	Medium
930	Binary Subarrays With Sum	Prefix Sum Hash Table	Medium
863	All Nodes Distance K in Binary Tree	DFS BFS	Medium
847	Shortest Path Visiting All Nodes	Bitmask BFS	Hard
802	Find Eventual Safe States	Topological Sort	Medium
743	Network Delay Time	DisjKstra Floyd	Medium
673	Number of Longest Increasing Subsequence	Dynamic Programming	Medium
611	Valid Triangle Number	Array Binary Search Sort	Medium
581	Shortest Unsorted Continuous Subarray	Array Sort	Medium
560	Subarray Sum Equals K	Prefix Sum Hash Table	Medium
475	Heaters	Array Binary Search	Medium
446	Arithmetic Slices II - Subsequence	DP	Hard
416	Partition Equal Subset Sum	DP	Medium
413	Arithmetic Slices	Prefix Sum Slicing Window	Medium
406	Queue Reconstruction by Height	Greedy Sort & Insert	Medium
378	Kth Smallest Element in a Sorted Matrix	Heap	Medium
349	Intersection of Two Arrays	Hash Table Binary Search	Simple
313	Super Ugly Number	Heap Hash Table Many Pointers	Medium
300	Longest Increasing Subsequence	Binary Search Dynamic Programming	Medium
275	H-Index II	Binary Search	Medium
274	H-Index	Sort Simulation	Medium
264	Ugly Number II	Heap Hash Table Dynamic Programming	Medium
229	Majority Element II	Moore Vote	Medium
218	The Skyline Problem	Heap Line Sweep	Hard
209	Minimum Size Subarray Sum	Sliding Window Two Pointers	Medium
191	Number of 1 Bits	Bit Manipulation	Simple
171	Excel Sheet Column Number	Math String	Simple
169	Majority Element	Moore Vote	Simple
160	Intersection of Two Linked Lists	Two Pointer	Simple
143	Reorder List	Link List Fast and slow pointers	Medium
138	Copy List with Random Pointer	Hash Table Link List	Medium
101	Symmetric Tree	Binary Tree	Simple
76	Minimum Window Substring	Hash Table Sliding Window	Hard
72	Edit Distance	Dynamic Programming	Hard
53	Maximum Subarray	Dynamic Programming	Simple
50	Pow(x, n)	Math	Medium
43	Multiply Strings	Simulation	Medium
34	Find First and Last Position of Element in Sorted Array	Binary Search	Medium

剑指 Offer

#	Title	Solution	Difficulty
61	扑克牌中的顺子	Math	Simple
60	n个骰子的点数	Dynamic Programming	Medium
59 - I	滑动窗口的最大值	Sliding Window Monotonic Queue Heap	Hard
56 - II	数组中数字出现的次数 II	Bit Manipulation	Medium
56 - I	数组中数字出现的次数	Bit Manipulation	Medium
55 - I	二叉树的深度	BFS DFS	Simple
53 - I	在排序数组中查找数字 I	Binary Search	Simple
52	两个链表的第一个公共节点	Hash Table Two Pointer	Simple
51	数组中的逆序对	Merge Sort	Hard
50	第一个只出现一次的字符	Hash Table	Simple
49	丑数	Heap	Medium
48	最长不含重复字符的子字符串	Hash Table Slicing Window	Medium
45	把数组排成最小的数	Sort	Medium
42	连续子数组的最大和	Dynamic Programming	Simple
40	最小的k个数	Array Sort	Simple
38	字符串的排列	Backtracing	Medium
37	序列化二叉树	Level Order Simulation	Hard
36	二叉搜索树与双向链表	inOrder	Medium
35	复杂链表的复制	Linklist HashTable Recursive	Medium
33	二叉搜索树的后序遍历序列	Binary Serach Tree	Medium
31	栈的压入、弹出序列	Stack Simulation	Medium
30	包含min函数的栈	Design Two Stacks	Simple
29	顺时针打印矩阵	Simulation	Simple
28	对称的二叉树	Tree Treversal	Simple
27	二叉树的镜像	Tree Treversal	Simple
26	树的子结构	Level Order Recursive	Medium
25	合并两个排序的链表	Two Pointers	Simple
24	反转链表	Recursive Two Pointers	Simple
22	链表中倒数第k个节点	Linklist Two Pointers	Simple
21	调整数组顺序使奇数位于偶数前面	Array Two Pointers	Simple
20	表示数值的字符串	String State Machine	Medium
18	删除链表的节点	Dummy Node Linklist	Simple
16	数值的整数次方	Math	Medium
15	二进制中1的个数	Math	Simple
14 - II	剪绳子	Greedy	Medium
14 - I	剪绳子	Dynamic Programming	Medium
13	机器人的运动范围	BFS DFS	Medium
12	矩阵中的路径	Backtracing	Medium
10 - II	青蛙跳台阶问题	记忆化搜索	Simple
10 - I	斐波那契数列	记忆化搜索	Simple
09	用两个栈实现队列	Simulation	Simple

面试题

#	Title	Solution	Difficulty
17.10	主要元素	Moore Vote	Simple
16.25	LRU 缓存	Hash Table Linked List	Medium
10.02	变位词组	Hash Table Sort	Medium

动态规划

股票问题

#	Title	Difficulty
121	Best Time to Buy and Sell Stock	Simple
122	Best Time to Buy and Sell Stock II	Simple
123	Best Time to Buy and Sell Stock III	Hard
188	Best Time to Buy and Sell Stock IV	Hard
309	Best Time to Buy and Sell Stock with Cooldown	Medium
714	Best Time to Buy and Sell Stock with Transaction Fee	Medium

打家劫舍

#	Title	Difficulty
198	House Robber	Medium
213	House Robber II	Medium
337	House Robber III	Medium

NowCoder

#	Title	Solution	Difficulty
华为机试题	扑克牌大小	String	Medium
华为机试题	简单错误记录	String	Medium
华为机试题	四则运算	Stack	Medium
华为机试题	最小公倍数	Math	Simple

Class

#	Type	Quantity	Feature
1	Array	9	binary search, slicing window, fast and slow pointer, simulate
2	Backtracing	17
3	Design	3
4	Dfs_Bfs	1
5	Divide_and_Conquer	2
6	DP	10
7	Greedy_algorithm	11
8	HashTable	8
9	Heap	2
10	List	8	new a dummy head node
11	Math	8
12	Search	4
13	Sort	3
14	Stack	8
15	String	10
16	Tree	31
17	Two pointers	11	sorted array, fast and slow pointer
18	Nowcoder	1

Notes

Useful Functions

STL	Func	Description	Lib
string	int isdigit(char ch)	isdigit('2')	<cstdio>
string	string substr(int pos, int len)	s.substr(0, 5))	<string>
string	void resize(int n)	s.resize(n))	<string>
string	int stoi("22")	string to int	<string>
string	empty(), back(), push_back(), pop_back()	just like a stack	<string>
map	insert(x)	element traversal only via the iterator:*it	<map>
map	iterator find(key)	mp.find(key)	<map>
vector	vec.push_back(vector<int>{1, 2, 3})	vector<vector<int> > vec	<vector>
vector	vec.assign(a.begin(), a.begin()+k)	copy data from a to vec	<vector>
vector	vec.emplace_back(ele)	similar to push_back(ele)	<vector>
-	reverse(vec.begin(), vec.end())	-	<algorithm>
unordered_set	insert(), find()	unordered_set tmp(vec.begin(), vec.end())	<unordered_set>
-	*max_element(vec.begin(), vec.end())	-	-

Useful template

• Divide&conquer: Merge_sort, Qucik_sort
• Backtracing: dfs, Backtracing
• Search: two_binary
• Tree: traversa, path
• Sliding Window
• Dynamic Programming
• DisjKstra&Floyd
• TopologicalSort

Hard understand

Problem
31.Next Permutation(Array)
264.Ugly Number II(DP)
347.Top K Frequent Elements(Heap)
239. Sliding Window Maximum(Monotonous queue)

Refer

• https://github.com/youngyangyang04/leetcode-master
• https://github.com/grandyang/leetcode
• https://github.com/labuladong/fucking-algorithm