| LC QNo. | name | Tag | Notes | Solution |
|---|---|---|---|---|
| 1 | Two Sum | easy | Solution | |
| 2 | Add 2 Num | medium | Solution | |
| 7 | Reverse Integer | easy | Overflow issues are a buzz kill | Solution |
| 11 | Container with Most Water | medium | Solution | |
| 13 | Roman to Integer | easy | Solution | |
| 20 | Valid Parentheses | easy | Solution | |
| 21 | Merge Two Sorted Lists | easy | Solution | |
| 22 | Generate Parentheses | medium | Solution | |
| 26 | Remove Duplicates from Sorted Array | easy | Solution | |
| 27 | Remove Element | easy | Solution | |
| 28 | Implement strStr() | easy | Solution | |
| 32 | Longest Valid Parentheses | hard | Solution | |
| 33 | Search in Rotated Sorted Array | medium | Solution | |
| 35 | Search Insert Position | easy | Solution | |
| 52 | N-Queens II | hard | Solution | |
| 53 | Maximum Subarray | easy | Solution | |
| 66 | Plus One | easy | Solution | |
| 69 | Sqrt(x) | easy | Solution | |
| 70 | Climbing Stairs | easy | Simple dp very basic, don’t use recursion, tc very bad | Solution |
| 83 | Remove Duplicates from Sorted List | easy | Solution | |
| 88 | Merge Sorted Array | easy | Solution | |
| 94 | Binary Tree Inorder Traversal | easy | Solution | |
| 97 | Interleaving String | medium | Solution | |
| 98 | Validate Binary Search Tree | medium | Solution | |
| 101 | Symmetric Tree | easy | Solution | |
| 102 | Binary Tree Level Order Traversal | medium | Solution | |
| 103 | Binary Tree Zigzag Level Order Traversal | medium | Solution | |
| 104 | Maximum Depth of Binary Tree | easy | Solution | |
| 108 | Convert Sorted Array to Binary Search Tree | easy | Solution | |
| 118 | Pascal's Triangle | easy | Solution | |
| 121 | Best Time to Buy and Sell Stock | easy | Solution | |
| 124 | Binary Tree Maximum Path Sum | hard | Solution | |
| 125 | Valid Palindrome | easy | Solution | |
| 128 | Longest Consecutive Sequence | medium | Sorting is simple and tc is O(NlogN). But use Set and HashMap to reduce it to O(N). Provided solution is much smarter | Solution |
| 136 | Single Number | easy | Solution | |
| 141 | Linked List Cycle | easy | Solution | |
| 144 | Binary Tree Preorder Traversal | easy | Solution | |
| 145 | Binary Tree Postorder Traversal | easy | Solution | |
| 146 | LRU Cache | medium | Solution | |
| 150 | Evaluate Reverse Polish Notation | medium | Solution | |
| 155 | Min Stack | easy | Solution | |
| 160 | Intersection of Two Linked Lists | easy | Solution | |
| 169 | Majority Element | easy | Solution | |
| 171 | Excel Sheet Column Number | easy | Solution | |
| 172 | Factorial Trailing Zeroes | easy | Solution | |
| 189 | Rotate Array | medium | Solution | |
| 190 | Reverse Bits | easy | Solution | |
| 191 | Number of 1 Bits | easy | Solution | |
| 200 | Number of Islands | medium | Solution | |
| 202 | Happy Number | easy | Solution | |
| 204 | Count Primes | easy | Solution | |
| 206 | Reverse Linked List | easy | Solution | |
| 217 | Contains Duplicate | easy | Solution | |
| 219 | Contains Duplicate II | easy | Solution | |
| 220 | Contains Duplicate III | medium | Solution | |
| 237 | Delete Node in a Linked List | easy | Solution | |
| 242 | Valid Anagram | easy | Solution | |
| 256 | Paint House | medium | Solution | |
| 268 | Missing Number | easy | Solution | |
| 278 | First Bad Version | easy | Solution | |
| 283 | Move Zeroes | easy | Solution | |
| 287 | Find the Duplicate Number | medium | Solution | |
| 318 | Maximum Product of Word Lengths | medium | Solution | |
| 326 | Power of Three | easy | Solution | |
| 344 | Reverse String | easy | Solution | |
| 347 | Top K Frequent Elements | medium | Solution | |
| 348 | Design Tic-Tac-Toe | medium | Solution | |
| 350 | Intersection of Two Arrays II | easy | Solution | |
| 371 | Sum of Two Integers | medium | Solution | |
| 384 | Shuffle an Array | medium | Solution | |
| 387 | First Unique Character in a String | easy | Solution | |
| 412 | Fizz Buzz | easy | Multiple solution, best one is which does not use modulo operation | Solution |
| 417 | Pacific Atlantic Water Flow | medium | Solution | |
| 448 | Find All Numbers Disappeared in an Array | easy | Solution | |
| 461 | Hamming Distance | easy | Solution | |
| 509 | Fibonacci Number | easy | Solution | |
| 551 | Student Attendance Record I | easy | Solution | |
| 557 | Reverse Words in a String III | easy | Solution | |
| 572 | Subtree of Another Tree | easy | Solution | |
| 583 | Delete Operation for Two Strings | medium | Solution | |
| 595 | Big Countries | easy | Solution | |
| 609 | Find Duplicate Flie in System | medium | Solution | |
| 617 | Merge Two Binary Trees | easy | Solution | |
| 630 | Course Schedule III | hard | Solution | |
| 647 | Palindromic Substrings | medium | Solution | |
| 665 | Non-decreasing Array | medium | Solution | |
| 695 | Max Area of Island | medium | Solution | |
| 700 | Search in a Binary Search Tree | easy | Solution | |
| 709 | To lower Case | easy | Solution | |
| 728 | Self Dividing Numbers | easy | Solution | |
| 745 | Prefix and Suffix Search | hard | Solution | |
| 752 | Open the Lock | medium | Solution | |
| 771 | Jewels and Stones | easy | Solution | |
| 804 | Unique Morse Code Words | easy | Solution | |
| 811 | Subdomain Visit Count | easy | Solution | |
| 841 | Keys and Rooms | medium | BFS simpler, can also use dfs | Solution |
| 869 | Reordered Power of 2 | medium | Solution | |
| 870 | Advantage Shuffle | medium | Solution | |
| 876 | Middle of the Linked List | easy | Solution | |
| 905 | Sort Array By Parity | easy | Solution | |
| 906 | Super Palindromes | hard | Solution | |
| 912 | Sort an Array | medium | Solution | |
| 916 | Word Subsets | medium | Solution | |
| 933 | Number of Recent Calls | easy | Solution | |
| 936 | Stamping the Sequence | hard | Solution | |
| 937 | Reorder Data in Log Files | easy | Custom comparator | Solution |
| 942 | DI String Match | easy | Solution | |
| 966 | Vowel Spellchecker | medium | Solution | |
| 977 | Squares of a Sorted Array | easy | Solution | |
| 1002 | Find Common Characters | easy | Solution | |
| 1010 | Pairs of Songs With Total Durations Divisible by 60 | medium | Use array to cache | Solution |
| 1041 | Robot Bounded In Circle | medium | Solution | |
| 1048 | Longest String Chain | medium | Solution | |
| 1108 | Defanging an IP address | easy | Solution | |
| 1167 | Minimum Cost to Connect Sticks | medium | Solution | |
| 1197 | Minimum Knight Moves | medium | Solution | |
| 1207 | Unique Number of Occurrences | easy | Solution | |
| 1217 | Minimum Cost to Move Chips to The Same Position | easy | Solution | |
| 1252 | Cells with Odd Values in a Matrix | easy | Solution | |
| 1268 | Search Suggestions System | medium | Solution | |
| 1281 | Subtract the Product and Sum of Digits of an Integer | easy | Solution | |
| 1290 | Convert Binary number in a linked list to Integer | easy | Solution | |
| 1295 | Find Numbers with Even Number of Digits | easy | Solution | |
| 1304 | Find N Unique Integers Sum up to Zero | easy | Solution | |
| 1313 | Decompress Run-Length Encoded List | easy | Solution | |
| 1342 | Number of Steps to Reduce a Number to Zero | easy | Solution | |
| 1365 | How Many Numbers Are Smaller Than the Current Number | easy | Constraints play a huge role | Solution |
| 1383 | Maximum Performance of a Team | hard | Solution | |
| 1423 | Maximum Poiints You Can Obtain from Cards | medium | Solution | |
| 1431 | Kids With the Greatest Number of Candies | easy | Solution | |
| 1441 | Build an Array With Stack Operations | easy | Solution | |
| 1460 | Make Two Arrays Equal by Reversing Sub-arrays | easy | Solution | |
| 1465 | Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts | medium | Solution | |
| 1470 | Shuffle the Array | easy | Solution | |
| 1476 | Subrectangle Queries | medium | Defining a class and performing operations | Solution |
| 1480 | Running Sum of 1d Array | easy | streamable option exists | Solution |
| 1486 | XOR Operation in an Array | easy | Solution | |
| 1491 | Average Salary Excluding the Minimum and Maximum Salary | easy | Solution | |
| 1512 | Number of Good Pairs | easy | Solution | |
| 1528 | Shuffle String | easy | Solution | |
| 1572 | Matrix Diagonal Sum | easy | Solution | |
| 1603 | Design Parking System | easy | Solution | |
| 1614 | Maximum Nesting Depth of the Parentheses | easy | Solution | |
| 1662 | Check If Two String Arrays are Equivalent | easy | Solution | |
| 1672 | Richest Customer Wealth | easy | Solution | |
| 1678 | Goal Parser Interpretation | easy | Solution | |
| 1684 | Count the Number of Consistent Strings | easy | Solution | |
| 1688 | Count of Matches in Tournament | easy | Solution | |
| 1689 | Partitioning Into Minimum Number of Deci-Binary Numbers | medium | Solution | |
| 1704 | Determine if String Halves Are Alike | easy | Solution | |
| 1720 | Decode XORed Array | easy | Solution | |
| 1732 | Find the Highest Altitude | easy | Solution | |
| 1748 | Sum of Unique Elements | easy | Solution | |
| 1768 | Merge Strings Alternately | easy | Solution | |
| 1769 | Minimum Number of Operations to Move All Balls to Each Box | medium | Solution | |
| 1773 | Count Items Matching a Rule | easy | Solution | |
| 1791 | Find Center of Star Graph | medium | Solution | |
| 1848 | Minimum Distance to the Target Element | easy | Solution | |
| 1880 | Check if Word Equals Summation of Two Words | easy | Solution | |
| 56 | Merge Intervals | medium | Sorting on arrival time and then comparing if they can be merged | Solution |
| 746 | Min Cost Climbing Stairs | easy | Simple dp with adding cost. Skip cost for base conditions | Solution |