sarstw / leetcode-solutions-in-swift

Get prepared for your next iOS job interview by studying high quality LeetCode solutions in Swift 2.1.

Before you start: Why do interviewers care so much about algorithm and data structure?

####LeetCode Solutions in Swift 2.1

• Designed for your next iOS job interview.
• Optimal solutions handpicked from the LeetCode community.
• Best time/space complexity guaranteed.
• Written with the latest Swift 2.1 language features in mind.
• Comprehensive test cases guarding against wrong answers and timeouts.
• A work in progress. Currently at 92 / ( 298 - 44 Paid Subscription ) = 36.2%, with 553 test cases.

#####Requires Xcode 7.2 Beta (Build 7C46l). Requires 64-bit simulators or devices to run test cases.

1. Two Sum - Medium - Swift Solution - ObjC Solution - Test Cases - t=O(N), s=O(N) - Inspired by @naveed.zafar
2. Add Two Numbers - Medium - Swift Solution - ObjC Solution - Test Cases - t=O(N), s=O(1) - Inspired by @potpie
3. Longest Substring Without Repeating Characters - Medium - Swift Solution - ObjC Solution - Test Cases - t=O(N), s=O(1) - Inspired by @heiyanbin
4. Median of Two Sorted Arrays - Hard - Swift Solution - ObjC Solution - Test Cases - t=O(log(min(m,n))), s=O(1) - Inspired by @MissMary - Be sure to read @MissMary's full explanation on how she achieved logarithmic time complexity with a few nice mathematic tricks.
5. Longest Palindromic Substring - Medium - Swift Solution - ObjC Solution - Test Cases - t=O(N^2), s=O(1) - Inspired by @hh1985
6. ZigZag Conversion - Easy - Solution - Test Cases - t=O(N), s=O(N) - Inspired by @dylan_yu
7. Reverse Integer - Easy - Solution - Test Cases - t=O(N), s=O(1) - Inspired by @wshaoxuan
8. String to Integer (atoi) - Easy - Solution - Test Cases - t=O(N), s=O(1) - Inspired by @yuruofeifei
9. Palindrome Number - Easy - Solution - Test Cases, t=O(N), s=O(1) - Inspired by @hln9319
10. Regular Expression Matching - Hard - Solution - Test Cases - DP, t=O(M*N), s=O(M*N) - Inspired by @xiaohui7
11. Container With Most Water - Medium - Solution - Test Cases - t=O(N), s=O(1) - Inspired by @franticguy
12. Integer To Roman - Medium - Solution - Test Cases - t=O(1), s=O(1) - Inspired by @flytosky
13. Roman To Integer - Easy - Solution - Test Cases - t=O(N), s=O(1) - Inspired by @makeittrue
14. Longest Common Prefix - Easy - Solution - Test Cases - t=O(N*M), s=O(1) - Inspired by @garysui
15. 3Sum - Medium - Solution - Test Cases - t=O(N^2), s=O(N) - Inspired by @peerlessbloom
16. 3Sum Closest - Medium - Solution - Test Cases - t=O(N^2), s=O(N)
17. Letter Combinations of A Phone Number - Medium - Solution - Test Cases - t=(3^N), s=O(3^N)
18. 4Sum - Medium - Solution - Test Cases - t=O(N^3), s=O(N)
19. Remove Nth Node From End of List - Easy - Solution - Test Cases - t=O(N), s=O(1)
20. Valid Parentheses - Easy - Solution - Test Cases - t=O(N), s=O(N)
21. Merge Two Sorted Lists - Easy - Solution - Test Cases - t=O(max(M,N)), s=O(1)
22. Generate Parentheses - Medium - Solution - Test Cases - t=O(N^2), s=O(N^2)
23. Merge K Sorted Lists - Hard - Solution - Test Cases - t=O(N*logK), s=O(logK), where where N is the total number of elements, K is the number of lists
24. Swap Nodes in Pairs - Medium - Solution - Test Cases, t=O(N), s=O(1)
25. Reverse Nodes in k-Group - Hard - Solution - Test Cases - t=O(N), s=O(1)
26. Remove Duplicates from Sorted Array - Easy - Solution - Test Cases - t=O(N), s=O(1)
27. Remove Element- Easy - Solution - Test Cases - t=O(N), s=O(1)
28. Implement strStr() - Easy - Solution - Test Cases - KMP: t=O(M+N), s=O(N). Brute-force: t=O(M*N), s=O(1).
29. Divide Two Integers - Medium - Solution - Test Cases - t=O((logN)^2), s=O(1)
30. Substring with Concatenation of All Words - Hard - Solution - Test Cases - t=O(N*W), s=O(L*W), where N is the length of the string, W is the length of a word, L is the length of the words list.
31. Next Permutation - Medium - Solution - Test Cases - t=O(N), s=O(1)
32. Longest Valid Parentheses - Hard - Solution - Test Cases - One pass, t=O(N), s=O(N)
33. Search in Rotated Sorted Array - Hard - Solution - Test Cases - t=O(logN), s=O(1)
34. Search for a Range - Medium - Solution - Test Cases - t=O(logN), s=O(1)
35. Search Insert Position - Medium - Solution - Test Cases - t=O(logN), s=O(1)
36. Valid Sudoku - Medium - Solution - Test Cases - t=O(1), s=O(1)
37. Sudoku Solver - Hard - Solution - Test Cases - DFS
38. Count and Say - Easy - Solution - Test Cases - t=(2^N), s=O(2^N)
39. Combination Sum - Medium - Solution - Test Cases - t=O(N*M), s=O(M), where N is the length of the candidates array, M is the value of the target integer.
40. Combination Sum II - Medium - Solution - Test Cases - t=O(N*M), s=O(M), where N is the length of the candidates array, M is the value of the target integer.
41. First Missing Positive - Hard - Solution - Test Cases - t=O(N), s=O(1)
42. Trapping Rain Water - Hard - Solution - Test Cases - t=O(N), s=O(1)
43. Multiply Strings - Medium - Solution - Test Cases - t=O(N*M), s=O(N+M)
44. Wildcard Matching - Hard - Solution - Test Cases - t=O(N), s=O(1)
45. Jump Game II - Hard - Solution - Test Cases - t=O(N), s=O(1)
46. Permutations - Medium - Solution - Test Cases - t=O(N!), s=O(N!)
47. Permutations II - Hard - Solution - Test Cases - t=O(N!), s=O(N!)
48. Rotate Image - Medium - Solution - Test Cases - t=O(N*N), s=O(1)
49. Anagrams - Medium - Solution - Test Cases - t=O(N), s=O(N)
50. Pow(x, n) - Medium - Solution - Test Cases - t=O(logN), s=O(logN)
51. N-Queens - Hard - Solution - Test Cases - t=O(N^2), s=O(N^2)
52. N-Queens II - Hard - Solution - Test Cases - t= well it's complicated...
53. Maximum Subarray - Medium - Solution - Test Cases - t=O(N), s=O(1)
54. Spiral Matrix - Medium - Solution - Test Cases - t=O(N), s=O(N)
55. Jump Game - Medium - Solution - Test Cases - t=O(N), s=O(1)
56. Merge Intervals - Hard - Solution - Test Cases - t=O(N*logN), s=O(N)
57. Insert Interval - Hard - Solution - Test Cases - t=O(N), s=O(N)
58. Length of Last Word - Easy - Solution - Test Cases - t=O(N), s=O(1)
59. Spiral Matrix II - Medium - Solution - Test Cases - t=O(N^2), s=O(N^2)
60. Permutation Sequence - Medium - Solution - Test Cases - t=O(N^2), s=O(N)
61. Rotate List - Medium - Solution - Test Cases - t=O(N), s=O(1)
62. Unique Paths - Medium - Solution - Test Cases - t=O(min(M, N)), s=O(1)
63. Unique Paths II - Medium - Solution - Test Cases - t=O(M*N), s=O(1)
64. Minimum Path Sum - Medium - Solution - Test Cases - t=O(M*N), s=O(1)
65. Valid Number - Hard - Solution - Test Cases - t=O(N), s=O(1)
66. Plus One - Easy - Solution - Test Cases - t=O(N), s=O(1)
67. Add Binary - Easy - Solution - Test Cases - t=O(max(M,N)), s=O(max(M,N))
68. Text Justification - Hard - Solution - Test Cases - t<=O(N*L), s<=O(N*L), where N is the length of the input words array, L is the required justified length
69. Sqrt(x) - Medium - Solution - Test Cases - t=O(logN), s=O(1)
70. Climbing Stairs - Easy - Solution - Test Cases - t=O(N), s=O(1)
71. Simplify Path - Medium - Solution - Test Cases - t=O(N), s=O(N)
72. Edit Distance - Hard - Solution - Test Cases - t=O(M*N), s=O(min(M,N))
73. Set Matrix Zeroes - Medium - Solution - Test Cases - t=O(M*N), s=O(1)
74. Search a 2D Matrix - Medium - Solution - Test Cases - t=O(logN), s=O(1)
75. Sort Colors - Medium - Solution - Test Cases - t=O(N), s=O(1), one pass
76. Minimum Window Substring - Hard - Solution - Test Cases - t=O(N), s=O(N)
77. Combinations - Medium - Solution - Test Cases - t=O(Combination(n, k)+2^(k-1)), s is complicated.
78. Subsets - Medium - Solution - Test Cases - t=O(N*2^N), s=O(n*2^N)
79. Word Search - Medium - Solution - Test Cases - t=O(M*N*L), s=O(L), where L is the length of the word.
80. Remove Duplicates from Sorted Array II - Medium - Solution - Test Cases - t=O(N), s=O(1)
81. Search in Rotated Sorted Array II - Medium - Solution - Test Cases - average t=O(logN), worst case t=O(N), s=O(1)
82. Remove Duplicates from Sorted List II - Medium - Solution - Test Cases - t=O(N), s=O(1)
83. Remove Duplicates from Sorted List - Easy - Solution - Test Cases - t=O(N), s=O(1) - Inspired by @Tao2014
84. Largest Rectangle in Histogram - Hard - Solution - Test Cases - t=O(N), s=O(N) - Inspired by geeksforgeeks
85. Maximal Rectangle - Hard - Solution - Test Cases - t=O(M*N), s=O(min(M,N)) - Inspired by @morrischen2008
86. Partition List - Medium - Solution - Test Cases - t=O(N), s=O(1) - Inspired by @shichaotan
87. Scramble String - Hard - Solution - Test Cases - time and space complexity need further investigation - Inspired by @Charles_p and @dtx0
88. Merge Sorted Array - Easy - Solution - Test Cases - t=O(N), s=O(1) - Inspired by @leetchunhui
89. Gray Code - Medium - Solution - Test Cases - t=O(2^N), s=O(2^N) - Inspired by @mike3
90. Subsets II - Medium - Solution - Test Cases - t=O(2^N), s=O(2^N) - Inspired by @mathsam
91. Decode Ways - Medium - Solution - Test Cases - t=O(N), s=O(N) - Inspired by @manky
92. Reverse Linked List II - Medium - Swift Solution - ObjC Solution - Test Cases - t=O(N), s=O(1), One Pass - Inspired by @ardyadipta

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