Summary

Codes I wrote to solve the problems on leetcode.

Most of the codes in Algorithm section are written in C++ and C,

and a few in Python, while the Shell section is in Perl.

A lot of the problems are solved in several ways, i.e. the naiive one and improved one.

Advices and discussions are welcome to Email to [email protected].

Enjoy it.

Catalogue

No.	#	Title	Difficulty	Solution
1	1	Two Sum	Easy	C++
2	2	Add Two Numbers	Medium	C++
3	3	Longest Substring Without Repeating Characters	Medium	C
4	7	Reverse Integer	Easy	C
5	8	String to Integer (atoi)	Easy	C
6	9	Palindrome Number	Easy	C
7	14	Longest Common Prefix	Easy	C++
8	17	Letter Combinations of a Phone Number	Medium	C++
9	19	Remove Nth Node From End of List	Easy	C
10	20	Valid Parentheses	Easy	C++
11	21	Merge Two Sorted Lists	Easy	C
12	22	Generate Parentheses	Medium	C++
13	24	Swap Nodes in Pairs	Easy	C
14	25	Reverse Nodes in k-Group	Hard	C++
15	25	Reverse Nodes in k-Group	Hard	C
16	26	Remove Duplicates from Sorted Array	Easy	C
17	27	Remove Element	Easy	C
18	28	Implement strStr()	Easy	C
19	33	Search in Rotated Sorted Array	Hard	C
20	33	Search in Rotated Sorted Array	Hard	C++
21	33	Search in Rotated Sorted Array	Hard	Python
22	33	Search in Rotated Sorted Array	Hard	C
23	35	Search Insert Position	Medium	C
24	36	Valid Sudoku	Easy	C++
25	37	Sudoku Solver	Hard	C++
26	39	Combination Sum	Medium	C++
27	40	Combination Sum II	Medium	C++
28	43	Multiply Strings	Medium	C++
29	46	Permutations	Medium	C++
30	51	N-Queens	Hard	C++
31	52	N-Queens II	Hard	C++
32	53	Maximum Subarray	Medium	C
33	55	Jump Game	Medium	C++
34	58	Length of Last Word	Easy	C
35	61	Rotate List	Medium	C
36	62	Unique Paths	Medium	C
37	66	Plus One	Easy	C++
38	67	Add Binary	Easy	C++
39	70	Climbing Stairs	Easy	C++
40	70	Climbing Stairs	Easy	C
41	73	Set Matrix Zeroes	Medium	C++
42	77	Combinations	Medium	C++
43	78	Subsets	Medium	C++
44	82	Remove Duplicates from Sorted List II	Medium	C
45	83	Remove Duplicates from Sorted List	Easy	C++
46	86	Partition List	Medium	C
47	88	Merge Sorted Array	Easy	C
48	90	Subsets II	Medium	C++
49	92	Reverse Linked List II	Medium	C
50	94	Binary Tree Inorder Traversal	Medium	C++
51	95	Unique Binary Search Trees II	Medium	C++
52	96	Unique Binary Search Trees	Medium	C++
53	100	Same Tree	Easy	C
54	101	Symmetric Tree	Easy	C
55	102	Binary Tree Level Order Traversal	Easy	C++
56	103	Binary Tree Zigzag Level Order Traversal	Medium	C++
57	104	Maximum Depth of Binary Tree	Easy	C
58	105	Construct Binary Tree from Preorder and Inorder Traversal	Medium	C++
59	106	Construct Binary Tree from Inorder and Postorder Traversal	Medium	C++
60	107	Binary Tree Level Order Traversal II	Easy	C++
61	108	Convert Sorted Array to Binary Search Tree	Medium	C++
62	109	Convert Sorted List to Binary Search Tree	Medium	C++
63	110	Balanced Binary Tree	Easy	C
64	111	Minimum Depth of Binary Tree	Easy	C
65	112	Path Sum	Easy	C++
66	113	Path Sum II	Medium	C++
67	118	Pascal's Triangle	Easy	Python
68	118	Pascal's Triangle	Easy	C++
69	119	Pascal's Triangle II	Easy	C++
70	120	Triangle	Medium	C++
71	125	Valid Palindrome	Easy	C
72	129	Sum Root to Leaf Numbers	Medium	C++
73	136	Single Number	Easy	Python
74	136	Single Number	Easy	C
75	139	Word Break	Medium	C++
76	141	Linked List Cycle	Easy	C
77	141	Linked List Cycle	Easy	C++
78	142	Linked List Cycle II	Medium	C
79	144	Binary Tree Preorder Traversal	Medium	C++
80	145	Binary Tree Postorder Traversal	Hard	C++
81	147	Insertion Sort List	Medium	C
82	147	Insertion Sort List	Medium	C++
83	148	Sort List	Medium	C
84	150	Evaluate Reverse Polish Notation	Medium	C++
85	151	Reverse Words in a String	Medium	C++
86	151	Reverse Words in a String	Medium	C
87	153	Find Minimum in Rotated Sorted Array	Medium	C
88	153	Find Minimum in Rotated Sorted Array	Medium	Python
89	155	Min Stack	Easy	C++
90	160	Intersection of Two Linked Lists	Easy	C
91	168	Excel Sheet Column Title	Easy	C++
92	168	Excel Sheet Column Title	Easy	C
93	169	Majority Element	Easy	C
94	169	Majority Element	Easy	C++
95	171	Excel Sheet Column Number	Easy	C
96	172	Factorial Trailing Zeroes	Easy	C
97	190	Reverse Bits	Easy	C
98	191	Number of 1 Bits	Easy	C
99	192	Word Frequency	Medium	Shell
100	193	Valid Phone Numbers	Easy	Shell
101	194	Transpose File	Medium	Shell
102	194	Transpose File	Medium	Perl
103	195	Tenth Line	Easy	Shell
104	198	House Robber	Easy	C
105	199	Binary Tree Right Side View	Medium	C++
106	201	Bitwise AND of Numbers Range	Medium	C++
107	202	Happy Number	Easy	C++
108	203	Remove Linked List Elements	Easy	C
109	204	Count Primes	Easy	C++
110	205	Isomorphic Strings	Easy	C++
111	206	Reverse Linked List	Easy	C
112	215	Kth Largest Element in an Array	Medium	C
113	216	Combination Sum III	Medium	C++
114	217	Contains Duplicate	Easy	C++
115	223	Rectangle Area	Easy	C++
116	225	Implement Stack using Queues	Easy	C++
117	226	Invert Binary Tree	Easy	C
118	228	Summary Ranges	Medium	C++
119	230	Kth Smallest Element in a BST	Medium	C++
120	231	Power of Two	Easy	C
121	232	Implement Queue using Stacks	Easy	C++
122	234	Palindrome Linked List	Easy	C++
123	235	Lowest Common Ancestor of a Binary Search Tree	Easy	C
124	237	Delete Node in a Linked List	Easy	C
125	238	Product of Array Except Self	Medium	C++
126	242	Valid Anagram	Easy	C
127	257	Binary Tree Paths	Easy	C++
128	258	Add Digits	Easy	Python
129	258	Add Digits	Easy	C
130	263	Ugly Number	Easy	C
131	264	Ugly Number II	Medium	C++
132	268	Missing Number	Medium	C
133	278	First Bad Version	Easy	C++
134	290	Word Pattern	Easy	Python
135	290	Word Pattern	Easy	C++
136	292	Nim Game	Easy	C++
137	344	Reverse String	Easy	C++
138	345	Reverse Vowels of a String	Easy	C++
139	349	Intersection of Two Arrays	Easy	C++
140	350	Intersection of Two Arrays II	Easy	C++
141	374	Guess Number Higher or Lower	Easy	C++
142	387	First Unique Character in a String	Easy	C++
143	387	First Unique Character in a String	Easy	Python
144	389	Find the Difference	Easy	Python
145	389	Find the Difference	Easy	C++
146	392	Is Subsequence	Medium	C++
147	392	Is Subsequence	Medium	Python
148	404	Sum of Left Leaves	Easy	C++
149	404	Sum of Left Leaves	Easy	Python