poxios / algorithm_study

Algorithm study with python and leetcode

Algorithm Study with LeetCode

• You can find original problems on leetcode by searching name in google

00. Problem_Name_Here/
├─ firstTry.py (My first try)
├─ better.py (Better way to solve)

• Table below was all written by me, based on my own thoughts.

Name	Difficulty	Fresh	Keywords
03. Reorder data in log files	Easy	Low
04. Most common word	Medium	Low
05. Group Anagrams	Medium	Medium	Sort
06. Palindromic Substring	Medium	High	Sliding window, Two pointer
07. Two Sum	Medium	High	List to dict, access using dict key
08. Trapping rain water	Hard	High	Two pointer, Stack, More study required
09. Sum of three numbers	Medium	Medium	Two pointer, Handling exception
10. Array partition I	Medium	Medium	Find rules
11. Product of array except self	Medium	High	O(n^2) to O(n)
12. Best Time to Buy and Sell Stock	Medium	High	Calculate min, max on all time
13. Palindrome linked list	Hard	High	Deque, Linked List, Runner
14. Merge two sorted lists	Medium	Medium	Recursion, Linked List
15. Reverse Linked List	Easy	Low	Recursion, Linked List
16. Add two numbers	Easy	Low	Linked List, Full adder
17. Swap nodes in pairs	Hard	High	Recursion, Linked List, More study required
18. Odd even linked list	Medium	Medium	Linked List
19. Reverse Linked List 2	Medium	Low	Linked List, Swap
20. Valid parentheses	Easy	Low	Stack
21. Remove Duplicate Letters	Hard	High	More study required, Stack
22. Daily temperatures	Medium	Medium	Stack
23. Implement stack using queues	Easy	Medium	Stack, Queue
24. Implement queue using stacks	Easy	Medium	Stack, Queue
25. Design circular queue	Medium	Medium	Circular queue
26. Design circular deque	Medium	Medium	Deque
27. Merge k sorted list	Medium	High	Heap, Heapq
28. Design hashmap	Easy	Low	Hashmap
29. Jewels and Stones	Easy	Low	Python skills
30. Longest substring without repeating characters	Hard	High	Two pointer, More study required
31. Top K Frequent Elements	Medium	High	Python skills, Counter
32. Number of islands	Medium	High	DFS, DFS with n*m array
33. Letter Combinations of a Phone Number	Medium	Medium	DFS
34. Permutations	Medium	Medium	DFS
35. Combinations	Medium	Medium	DFS
36. Combination Sum	Medium	Medium	DFS
37. Subsets	Medium	Medium	DFS
38. Reconstruct Itinerary	Hard	Medium	DFS in bothways, More study required
39. Course Schedule	?	?	?
40. Network delay time	Medium	Medium	BFS, Dijkstra
41. Cheapest Flights Within K Stops	Hard	High	Dijkstra, More study required
42. Maximum Depth of Binary Tree	Medium	Low	BFS, Tree
43. Diameter of Binary Tree	Medium	High	BFS, Tree, Longest path of tree
44. Longest Univalue Path	Hard	High	BFS, Tree, Longest path of tree
45. Invert Binary Tree	Medium	Medium	Invert tree
46. Merge Two Binary Trees	Medium	High	Merge tree, Retry required
47. Serialize and Deserialize Binary Tree	Hard	High	Encode tree with BFS, Retry required
48. Balanced Binary Tree	Hard	High	Tree height calc, Retry required