Important Questions:
| Problem # | Problem | Solution | Difficulty Level | DONE |
|---|---|---|---|---|
|
1 |
Median of Two Sorted Arrays |
Solution | EASY | |
| 2 |
Regular Expression Matching | Solution | EASY | |
| 3 |
Letter Combinations of a Phone Number | Solution | EASY | |
| 4 |
Valid Parentheses | Solution | EASY | |
| 5 |
Generate Parentheses | Solution | EASY | |
| 6 |
Merge k Sorted Lists | Solution | EASY | |
| 7 |
Next Permutation | Solution | EASY | |
| 8 |
Trapping Rain Water | Solution | EASY | |
| 9 |
Wildcard Matching | Solution | EASY | |
| 10 | Pow(x, n) | Solution | EASY | |
| 11 | Spiral Matrix | Solution | EASY | |
|
12
|
Merge Intervals | Solution | EASY | |
|
13
|
Insert Interval
|
Solution | EASY | |
| 14 | Plus One | Solution | EASY | |
|
15
|
Longest Consecutive Sequence | Solution | EASY | |
|
16
|
Clone Graph | Solution | EASY | |
| 17 | Word Break | Solution | EASY | |
| 18 | Word Break II | Solution | EASY | |
| 19 | LRU Cache | Solution | EASY | |
| 20 | Min Stack | Solution | EASY | |
|
21
|
Find Peak Element | Solution | EASY | |
|
22
|
Fraction to Recurring Decimal | Solution | EASY | |
| 23 | Binary Search Tree Iterator | Solution | EASY | |
| 24 | Number of Islands | Solution | EASY | |
| 25 | Implement Trie (Prefix Tree) | Solution | EASY | |
| 25 | Word Search II | Solution | EASY | |
| 26 | Shortest Palindrome | Solution | EASY | |
| 27 | The Skyline Problem | Solution | EASY | |
| 28 | Basic Calculator | Solution | EASY | |
|
29
|
Summary Ranges | Solution | EASY | |
| 30 |
Kth Smallest Element in a BST | Solution | EASY | |
| 31 | Power of Two | Solution | EASY | |
|
32
|
Sliding Window Maximum | Solution | EASY | |
| 33 | Search a 2D Matrix II | Solution | EASY | |
| 34 | Binary Tree Paths | Solution | EASY | |
| 35 | H-Index | Solution | EASY | |
| 36 | Perfect Squares | Solution | EASY | |
| 37 | Expression Add Operators | Solution | EASY | |
| 38 | Peeking Iterator | Solution | EASY | |
| 39 |
Game of Life | Solution | EASY | |
| 40 | Find Median from Data Stream | Solution | EASY | |
| 41 | Serialize and Deserialize Binary Tree | Solution | MEDIUM | |
| 42 |
Best Time to Buy and Sell Stock with Cooldown |
Solution | MEDIUM | |
| 43 |
Minimum Height Trees |
Solution | MEDIUM | |
| 44 | Burst Balloons | Solution | MEDIUM | |
| 45 | Super Ugly Number | Solution | MEDIUM | |
| 46 | Count of Smaller Numbers After Self | Solution | MEDIUM | |
| 47 | Remove Duplicate Letters | Solution | MEDIUM | |
| 48 | Maximum Product of Word Lengths | Solution | MEDIUM | |
| 49 |
Create Maximum Number | Solution | MEDIUM | |
| 50 |
Wiggle Sort II
|
Solution | MEDIUM | |
| 51 |
Power of Three | Solution | MEDIUM | |
| 52 | Count of Range Sum | Solution | MEDIUM | |
| 53 | Longest Increasing Path in a Matrix | Solution | MEDIUM | |
| 54 | Patching Array | Solution | MEDIUM | |
| 55 |
Verify Preorder Serialization of a Binary Tree |
Solution | MEDIUM | |
| 56 | Reconstruct Itinerary | Solution | MEDIUM | |
| 57 | Palindrome Pairs | Solution | MEDIUM | |
| 58 | Flatten Nested List Iterator | Solution | MEDIUM | |
| 59 |
Reverse Vowels of a String | Solution | MEDIUM | |
| 60 |
Russian Doll Envelopes | Solution | MEDIUM | |
| 61 | Count Numbers with Unique Digits | Solution | MEDIUM | |
| 62 | Max Sum of Rectangle No Larger Than K | Solution | MEDIUM | |
| 63 | Largest Divisible Subset | Solution | MEDIUM | |
| 64 | Find K Pairs with Smallest Sums | Solution | MEDIUM | |
| 65 | Guess Number Higher or Lower | Solution | MEDIUM | |
| 66 | Guess Number Higher or Lower II | Solution | MEDIUM | |
| 67 | Combination Sum IV | Solution | MEDIUM | |
| 68 | Kth Smallest Element in a Sorted Matrix | Solution | MEDIUM | |
| 69 |
Insert Delete GetRandom O(1) | Solution | MEDIUM | |
| 70 | Linked List Random Node | Solution | MEDIUM | |
| 71 | Longest Absolute File Path | Solution | MEDIUM | |
| 72 |
Find the Difference |
Solution | MEDIUM | |
| 73 | Perfect Rectangle | Solution | MEDIUM | |
| 74 | UTF-8 Validation | Solution | MEDIUM | |
| 75 | Decode String | Solution | MEDIUM | |
| 76 | Integer Replacement | Solution | MEDIUM | |
| 77 | Evaluate Division | Solution | MEDIUM | |
| 78 | Nth Digit | Solution | MEDIUM | |
| 79 |
Binary Watch | Solution | MEDIUM | |
| 80 | Remove K Digits | Solution | MEDIUM | |
| 81 | Queue Reconstruction by Height | Solution | MEDIUM | |
|
82
|
Trapping Rain Water II | Solution | MEDIUM | |
| 83 | Longest Palindrome | Solution | MEDIUM | |
| 84 | Add Strings | Solution | MEDIUM | |
| 85 | Pacific Atlantic Water Flow | Solution | MEDIUM | |
| 86 | Maximum XOR of Two Numbers in an Array | Solution | MEDIUM | |
| 87 | Number of Boomerangs | Solution | MEDIUM | |
|
88
|
Find All Numbers Disappeared in an Array | Solution | MEDIUM | |
|
89
|
Sort Characters By Frequency | Solution | MEDIUM | |
| 90 |
Repeated Substring Pattern | Solution | MEDIUM | |
|
91
|
LFU Cache | Solution | MEDIUM | |
| 92 | Island Perimeter | Solution | MEDIUM | |
| 93 | Ones and Zeroes | Solution | MEDIUM | |
| 94 | Heaters | Solution | MEDIUM | |
| 95 | Sliding Window Median | Solution | MEDIUM | |
| 96 | Magical String | Solution | MEDIUM | |
| 97 | License Key Formatting | Solution | MEDIUM | |
| 98 | Smallest Good Base | Solution | MEDIUM | |
| 99 |
Max Consecutive Ones | Solution | MEDIUM | |
|
100
|
Predict the Winner | Solution | MEDIUM | |
| 101 | Reverse Pairs | Solution | MEDIUM | |
| 102 | Target Sum | Solution | MEDIUM | |
| 103 |
Diagonal Traverse |
Solution | MEDIUM | |
|
104
|
Find Mode in Binary Search Tree | Solution | MEDIUM | |
|
105
|
Next Greater Element II | Solution | MEDIUM | |
|
106
|
Relative Ranks | Solution | MEDIUM | |
|
107
|
Freedom Trail | Solution | MEDIUM | |
|
108
|
Detect Capital | Solution | MEDIUM | |
|
109
|
Longest Uncommon Subsequence I | Solution | MEDIUM | |
|
110 |
Longest Uncommon Subsequence II | Solution | MEDIUM | |
|
111 |
Longest Word in Dictionary through Deleting | Solution | MEDIUM | |
|
112 |
Beautiful Arrangement | Solution | MEDIUM | |
|
113 |
Minimum Absolute Difference in BST | Solution | MEDIUM | |
|
114 |
Encode and Decode TinyURL | Solution | MEDIUM | |
|
115 |
Reverse String II | Solution | MEDIUM | |
|
116 |
01 Matrix | Solution | MEDIUM | |
|
117 |
Diameter of Binary Tree | Solution | MEDIUM | |
|
118 |
Student Attendance Record I | Solution | MEDIUM | |
|
119 |
Student Attendance Record II | Solution | MEDIUM | |
|
120 |
Subarray Sum Equals K
|
Solution | MEDIUM | |
|
121 |
Subtree of Another Tree | Solution | MEDIUM | |
|
122 |
Shortest Unsorted Continuous Subarray | Solution | MEDIUM | |
|
123 |
Delete Operation for Two Strings | Solution | MEDIUM | |
|
124 |
Erect the Fence | Solution | MEDIUM | |
|
125 |
Shopping Offers | Solution | MEDIUM | |
|
126 |
Maximum Average Subarray I | Solution | MEDIUM | |
|
127 |
Find Duplicate Subtrees | Solution | MEDIUM | |
|
128 |
Robot Return to Origin | Solution | MEDIUM | |
|
129 |
Find K Closest Elements | Solution | MEDIUM | |
|
130 |
Split Array into Consecutive Subsequences | Solution | MEDIUM | |
131 |
Non-decreasing Array | Solution | MEDIUM | |
|
132 |
Beautiful Arrangement II | Solution | MEDIUM | |
133 |
Kth Smallest Number in Multiplication Table | Solution | MEDIUM | |
|
134 |
Implement Magic Dictionary | Solution | MEDIUM | |
|
135 |
24 Game |
Solution | MEDIUM | |
|
136 |
Redundant Connection | Solution | MEDIUM | |
|
137 |
Redundant Connection II | Solution | MEDIUM | |
|
138 |
Repeated String Match | Solution | MEDIUM | |
|
139 |
Longest Univalue Path | Solution | MEDIUM | |
|
141 |
Maximum Sum of 3 Non-Overlapping Subarrays | Solution | MEDIUM | |
|
142 |
Find K-th Smallest Pair Distance | Solution | MEDIUM | |
|
143 |
Number of Atoms | Solution | MEDIUM | |
|
144 |
My Calendar I | Solution | HARD | |
|
145 |
My Calendar II |
Solution | HARD |