ゼロから始めるLeetCode 目次

概要

海外ではエンジニアの面接においてコーディングテストというものが行われるらしく、多くの場合、特定の関数やクラスをお題に沿って実装するという物がメインである。

どうやら多くのエンジニアはその対策としてLeetCodeなるサイトで対策を行うようだ。

早い話が本場でも行われているようなコーディングテストに耐えうるようなアルゴリズム力を鍛えるサイトであり、海外のテックカンパニーでのキャリアを積みたい方にとっては避けては通れない道である。

と、仰々しく書いてみましたが、私は今のところそういった面接を受ける予定はありません。

ただ、ITエンジニアとして人並みのアルゴリズム力くらいは持っておいた方がいいだろうということで不定期に問題を解いてその時に考えたやり方をメモ的に書いていこうかと思います。

Leetcode

Python3で解いています。

リンク集

この記事をストックしておくと新しい記事の追加時に通知されます。

コードだけ見たい方はこちらの
Githubをご覧ください。

番号はLeetCodeの問題へのリンク、問題のリンクは解説記事についてのリンクです。

間違えているリンク等あればコメント頂けると幸いです。

Day	番号	問題	難易度
1	1389	Create Target Array in the Given Order	Easy
2	1108	Defanging an IP Address	Easy
3	1313	Decompress Run-Length Encoded List	Easy
4	938	Range Sum of BST	Easy
5	1266	Minimum Time Visiting All Points	Easy
6	1342	Number of Steps to Reduce a Number to Zero	Easy
7	104	Maximum Depth of Binary Tree	Easy
8	1302	Deepest Leaves Sum	Medium
9	701	Insert into a Binary Search Tree	Medium
10	1431	Kids With the Greatest Number of Candies	Easy
11	1315	Sum of Nodes with Even-Valued Grandparent	Medium
12	617	Merge Two Binary Trees	Easy
13	338	Counting Bits	Medium
14	136	Single Number	Easy
15	283	Move Zeroes	Easy
16	344	Reverse String	Easy
17	169	Majority Element	Easy
18	53	Maximum Subarray	Easy
19	121	Best Time to Buy and Sell Stock	Easy
20	134	Gas Station	Medium
21	448	Find All Numbers Disappeared in an Array	Easy
22	141	Linked List Cycle	Easy
23	226	Invert Binary Tree	Easy
24	21	Merge Two Sorted Lists	Easy
25	70	Climbing Stairs	Easy
26	94	Binary Tree Inorder Traversal	Easy
27	101	Symmetric Tree	Easy
28	198	House Robber	Easy
29	46	Permutations	Medium
30	234	Palindrome Linked List	Easy
31	581	Shortest Unsorted Continuous Subarray	Easy
32	437	Path Sum III	Easy
33	1	Two Sum	Easy
34	118	Pascal’s Triangle	Easy
35	160	Intersection of Two Linked Lists	Easy
36	155	Min Stack	Easy
37	105	Construct Binary Tree from Preorder and Inorder Traversal	Medium
38	208	Implement Trie (Prefix Tree)	Medium
39	494	Target Sum	Medium
40	114	Flatten Binary Tree to Linked List	Medium
41	394	Decode String	Medium
42	2	Add Two Numbers	Medium
43	5	Longest Palindromic Substring	Medium
44	543	Diameter of Binary Tree	Easy
45	1379	Find a Corresponding Node of a Binary Tree in a Clone of That Tree	Medium
46	406	Queue Reconstruction by Height	Medium
47	14	Longest Common Prefix	Easy
48	26	Remove Duplicates from Sorted Array	Easy
49	1323	Maximum 69 Number	Easy
50	739	Daily Temperatures	Medium
51	647	Palindromic Substrings	Medium
52	1351	Count Negative Numbers in a Sorted Matrix」	Medium
53	1365	How Many Numbers Are Smaller Than the Current Number	Easy
54	1290	Convert Binary Number in a Linked List to Integer	Easy
55	22	Generate Parentheses	Medium
56	1480	Running Sum of 1d Array	Easy
57	35	Search Insert Position	Easy
58	20	Valid Parentheses	Easy
59	1221	Split a String in Balanced Strings	Easy
60	1481	Least Number of Unique Integers after K Removals	Medium
61	7	Reverse Integer	Easy
62	83	Remove Duplicates from Sorted List	Easy
63	195	Tenth Line	Easy
64	287	Find the Duplicate Number	Medium
65	560	Subarray Sum Equals K)	Medium
66	438	Find All Anagrams in a String	Medium
67	1486	XOR Operation in an Array	Easy
68	709	To Lower Case	Easy
69	279	Perfect Squares	Medium
70	295	Find Median from Data Stream	Hard
71	1496	Path Crossing	Easy
72	1498	Number of Subsequences That Satisfy the Given Sum Condition	Medium
73	1491	Average Salary Excluding the Minimum and Maximum Salary	Easy
74	12	Integer to Roman	Medium
75	15	3Sum	Medium
76	3	Longest Substring Without Repeating Characters	Medium
77	1502	Can Make Arithmetic Progression From Sequence	Easy
78	206	Reverse Linked List	Easy
79	1282	Group the People Given the Group Size They Belong To	Medium
80	703	Kth Largest Element in a Stream	Easy
81	347	Top K Frequent Elements	Medium
82	392	Is Subsequence	Easy
83	102	Binary Tree Level Order Traversal	Medium
84	142	Linked List Cycle Ⅱ	Medium
85	6	ZigZag Conversion	Medium
86	33	Search in Rotated Sorted Array	Medium
87	1512	Number of Good Pairs	Easy
88	139	Word Break	Medium
89	62	Unique Paths	Medium
90	1011	Capacity To Ship Packages Within D Days	Medium
91	153	Find Minimum in Rotated Sorted Array	Medium
92	4	Median of Two Sorted Arrays	Hard
93	49	Group Anagrams	Medium
94	929	Unique Email Addresses	Easy
95	82	Remove Duplicates from Sorted List II	Medium
96	78	Subsets	Medium
97	349	Intersection of Two Arrays	Easy
98	39	Combination Sum	Medium
99	112	Path Sum	Easy
100	108	Convert Sorted Array to Binary Search Tree	Easy
101	387	First Unique Character in a String	Easy
102	322	Coin Change	Medium
103	12	Best Time to Buy and Sell Stock II	Easy
104	103	Binary Tree Zigzag Level Order Traversal	Medium
105	111	Minimum Depth of Binary Tree	Easy
106	209	Minimum Size Subarray Sum	Medium
107	98	Validate Binary Search Tree	Medium
108	300	Longest Increasing Subsequence	Medium
109	213	House Robber II	Medium
110	1535	Find the Winner of an Array Game	Medium