LeetCode OJ
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Announcement

Great news for Ruby programmers: LeetCode OJ now supports Ruby!
Currently 27 problems were translated to Ruby ([12] [13] [19] [94] [121] [122] [123] [144] [145] [168] [171] [172] [188] [189] [190] [191]) and more is coming soon!

If you would like to contribute to the translations, we are interested to hear from you!

CONGRATULATIONS

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Welcome, ! You have solved problems.
191 Number of 1 Bits 38.3% Easy
190 Reverse Bits 27.9% Easy
189 Rotate Array 17.7% Easy
188 Best Time to Buy and Sell Stock IV 16.0% Hard
187 Repeated DNA Sequences 18.8% Medium
186 Reverse Words in a String II 31.6% Medium
179 Largest Number 15.4% Medium
174 Dungeon Game 17.2% Hard
173 Binary Search Tree Iterator 28.9% Medium
172 Factorial Trailing Zeroes 27.5% Easy
171 Excel Sheet Column Number 36.9% Easy
170 Two Sum III - Data structure design 24.6% Easy
169 Majority Element 34.5% Easy
168 Excel Sheet Column Title 17.6% Easy
167 Two Sum II - Input array is sorted 43.9% Medium
166 Fraction to Recurring Decimal 12.2% Medium
165 Compare Version Numbers 15.0% Easy
164 Maximum Gap 24.2% Hard
163 Missing Ranges 23.5% Medium
162 Find Peak Element 32.5% Medium
161 One Edit Distance 25.2% Medium
160 Intersection of Two Linked Lists 27.5% Easy
159 Longest Substring with At Most Two Distinct Characters 29.9% Hard
158 Read N Characters Given Read4 II - Call multiple times 21.0% Hard
157 Read N Characters Given Read4 28.7% Easy
156 Binary Tree Upside Down 34.6% Medium
155 Min Stack 16.5% Easy
154 Find Minimum in Rotated Sorted Array II 31.4% Hard
153 Find Minimum in Rotated Sorted Array 32.9% Medium
152 Maximum Product Subarray 18.7% Medium
151 Reverse Words in a String 14.9% Medium
150 Evaluate Reverse Polish Notation 20.7% Medium
149 Max Points on a Line 12.1% Hard
148 Sort List 21.5% Medium
147 Insertion Sort List 26.0% Medium
146 LRU Cache 14.7% Hard
145 Binary Tree Postorder Traversal 31.9% Hard
144 Binary Tree Preorder Traversal 36.2% Medium
143 Reorder List 20.9% Medium
142 Linked List Cycle II 31.2% Medium
141 Linked List Cycle 36.3% Medium
140 Word Break II 17.3% Hard
139 Word Break 22.4% Medium
138 Copy List with Random Pointer 24.5% Hard
137 Single Number II 34.6% Medium
136 Single Number 45.4% Medium
135 Candy 20.1% Hard
134 Gas Station 25.8% Medium
133 Clone Graph 23.7% Medium
132 Palindrome Partitioning II 19.3% Hard
131 Palindrome Partitioning 26.3% Medium
130 Surrounded Regions 14.6% Medium
129 Sum Root to Leaf Numbers 30.4% Medium
128 Longest Consecutive Sequence 29.1% Hard
126 Word Ladder II 12.4% Hard
127 Word Ladder 19.1% Medium
125 Valid Palindrome 22.1% Easy
124 Binary Tree Maximum Path Sum 21.1% Hard
123 Best Time to Buy and Sell Stock III 23.5% Hard
122 Best Time to Buy and Sell Stock II 37.9% Medium
121 Best Time to Buy and Sell Stock 32.3% Medium
120 Triangle 27.0% Medium
119 Pascal's Triangle II 29.7% Easy
118 Pascal's Triangle 30.6% Easy
117 Populating Next Right Pointers in Each Node II 31.7% Hard
116 Populating Next Right Pointers in Each Node 36.1% Medium
115 Distinct Subsequences 25.9% Hard
114 Flatten Binary Tree to Linked List 28.7% Medium
113 Path Sum II 26.7% Medium
112 Path Sum 29.9% Easy
111 Minimum Depth of Binary Tree 29.2% Easy
110 Balanced Binary Tree 32.1% Easy
109 Convert Sorted List to Binary Search Tree 27.7% Medium
108 Convert Sorted Array to Binary Search Tree 33.8% Medium
107 Binary Tree Level Order Traversal II 30.8% Easy
106 Construct Binary Tree from Inorder and Postorder Traversal 26.7% Medium
105 Construct Binary Tree from Preorder and Inorder Traversal 26.5% Medium
104 Maximum Depth of Binary Tree 44.9% Easy
103 Binary Tree Zigzag Level Order Traversal 26.5% Medium
102 Binary Tree Level Order Traversal 29.6% Easy
101 Symmetric Tree 31.5% Easy
100 Same Tree 42.1% Easy
99 Recover Binary Search Tree 24.3% Hard
98 Validate Binary Search Tree 21.7% Medium
97 Interleaving String 20.3% Hard
95 Unique Binary Search Trees II 27.6% Medium
96 Unique Binary Search Trees 37.1% Medium
94 Binary Tree Inorder Traversal 36.1% Medium
93 Restore IP Addresses 20.8% Medium
92 Reverse Linked List II 26.3% Medium
90 Subsets II 27.5% Medium
91 Decode Ways 16.4% Medium
89 Gray Code 32.6% Medium
88 Merge Sorted Array 30.1% Easy
87 Scramble String 23.9% Hard
86 Partition List 27.4% Medium
85 Maximal Rectangle 21.9% Hard
84 Largest Rectangle in Histogram 22.4% Hard
82 Remove Duplicates from Sorted List II 24.9% Medium
83 Remove Duplicates from Sorted List 34.3% Easy
81 Search in Rotated Sorted Array II 31.6% Medium
80 Remove Duplicates from Sorted Array II 30.7% Medium
79 Word Search 20.0% Medium
78 Subsets 28.2% Medium
77 Combinations 30.5% Medium
76 Minimum Window Substring 18.6% Hard
75 Sort Colors 32.6% Medium
74 Search a 2D Matrix 31.4% Medium
73 Set Matrix Zeroes 31.4% Medium
72 Edit Distance 26.1% Hard
71 Simplify Path 20.1% Medium
70 Climbing Stairs 34.1% Easy
69 Sqrt(x) 22.9% Medium
68 Text Justification 14.4% Hard
66 Plus One 30.9% Easy
65 Valid Number 11.4% Hard
67 Add Binary 25.0% Easy
21 Merge Two Sorted Lists 33.1% Easy
64 Minimum Path Sum 31.7% Medium
63 Unique Paths II 28.0% Medium
62 Unique Paths 32.7% Medium
61 Rotate List 21.8% Medium
60 Permutation Sequence 22.7% Medium
59 Spiral Matrix II 31.5% Medium
58 Length of Last Word 28.6% Easy
57 Insert Interval 21.1% Hard
56 Merge Intervals 21.9% Hard
55 Jump Game 27.3% Medium
54 Spiral Matrix 20.8% Medium
53 Maximum Subarray 34.6% Medium
52 N-Queens II 35.1% Hard
51 N-Queens 26.2% Hard
50 Pow(x, n) 26.8% Medium
49 Anagrams 24.3% Medium
48 Rotate Image 31.7% Medium
47 Permutations II 25.7% Hard
46 Permutations 31.8% Medium
45 Jump Game II 24.6% Hard
44 Wildcard Matching 15.0% Hard
43 Multiply Strings 20.8% Medium
42 Trapping Rain Water 30.1% Hard
41 First Missing Positive 23.1% Hard
40 Combination Sum II 25.1% Medium
39 Combination Sum 27.8% Medium
38 Count and Say 25.7% Easy
37 Sudoku Solver 21.4% Hard
36 Valid Sudoku 27.2% Easy
35 Search Insert Position 35.5% Medium
34 Search for a Range 27.7% Medium
33 Search in Rotated Sorted Array 29.0% Hard
32 Longest Valid Parentheses 20.5% Hard
31 Next Permutation 25.1% Medium
30 Substring with Concatenation of All Words 19.2% Hard
29 Divide Two Integers 15.5% Medium
28 Implement strStr() 22.0% Easy
27 Remove Element 32.4% Easy
26 Remove Duplicates from Sorted Array 31.6% Easy
25 Reverse Nodes in k-Group 25.3% Hard
24 Swap Nodes in Pairs 32.6% Medium
23 Merge k Sorted Lists 21.2% Hard
22 Generate Parentheses 32.4% Medium
20 Valid Parentheses 26.7% Easy
19 Remove Nth Node From End of List 28.0% Easy
17 Letter Combinations of a Phone Number 26.3% Medium
18 4Sum 21.4% Medium
16 3Sum Closest 27.0% Medium
15 3Sum 16.9% Medium
14 Longest Common Prefix 26.3% Easy
13 Roman to Integer 34.8% Easy
12 Integer to Roman 34.5% Medium
11 Container With Most Water 31.9% Medium
10 Regular Expression Matching 20.7% Hard
9 Palindrome Number 29.3% Easy
8 String to Integer (atoi) 13.5% Easy
7 Reverse Integer 28.2% Easy
6 ZigZag Conversion 22.4% Easy
5 Longest Palindromic Substring 20.8% Medium
2 Add Two Numbers 22.5% Medium
3 Longest Substring Without Repeating Characters 21.6% Medium
4 Median of Two Sorted Arrays 17.8% Hard
1 Two Sum 18.0% Medium
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