Playground for Leetcode Questions.
Trying to solve every question with as many solutions as I can.
Now in Phase II!
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Phase II Review all the questions completed so far, add "code tags" to each of them, try to cover similar questions if necessary.
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Phase I Complete 150 questions.
Question Table
Updating ~~~
1. array
| # | *** | Name | Code Tags | Groups |
|---|---|---|---|---|
| 1 | E | Two Sum | Sort + Two Pointers, Hashtable | K-Sum |
| 15 | M | Three Sum | Sort + Two Pointers | K-Sum |
| 18 | M | Four Sum | Sort + Two Pointers, Backtracking | K-Sum |
| 167 | M | Two Sum Sorted | Sort + Two Pointers, Hashtable, Binary Search | K-Sum |
| 170 | E | Two Sum Data Structure | Hashtable | K-Sum |
| 16 | M | Three Sum Closest | Sort + Two Pointers | K-Sum |
| 259 | M | Three Sum Smaller | Sort + Two Pointers | K-Sum |
| 26 | E | Remove Duplicates From Sorted Array | Two Pointers | - |
| 27 | E | Remove Element | Two Pointers | - |
| 66 | E | Plus One | Math: Carry | - |
| 88 | E | Merge Sorted Array | Two Pointers, Reverse Scan, Sentinel | - |
| 118 | E | Pascal Triangle | Reverse Scan, Sentinel | Pascal Triangle |
| 119 | E | Pascal Triangle 2 | Reverse Scan, DP | Pascal Triangle |
| 136 | E | Single Number | XOR | Single Number |
| 137 | M | Single Number 2 | XOR | Single Number |
| 260 | M | Single Number 3 | XOR | Single Number |
| 169 | E | Majority Element | Moore Voting, Hashtable, Sort | Majority Element |
| 229 | M | Majority Element 2 | Moore Voting, Hashtable | Majority Element |
| 189 | E | Rotate Array | Divide & Conquer, Two Pointers | - |
| 191 | E | Hamming Weight | Bit Manipulation | Hamming |
| 461 | E | Hamming Distance | Bit Manipulation | Hamming |
| 217 | E | Contains Duplicate | Hashtable, Sort | Contains Duplicate |
| 219 | E | Contains Duplicate 2 | Hashtable, Sliding Window | Contains Duplicate |
| 220 | M | Contains Duplicate 3 | Bucket Sort, TreeSet, Sliding Window | Contains Duplicate |
| 243 | E | Shortest Word Distance | Two Pointers, Sentinel | Word Distance |
| 244 | M | Shortest Word Distance 2 | Two Pointers, Hashtable, String | Word Distance |
| 245 | M | Shortest Word Distance 3 | Two Pointers | Word Distance |
| 283 | E | Move Zeroes | Two Pointers | - |
| 4 | H | Median of Two Sorted Arrays | Binary Search, Two Pointers | - |
| 33 | H | Search Rotated Array | Binary Search, Two Pointers, Rotation | Rotated Sorted Array |
| 81 | M | Search Rotated Array 2 | Binary Search, Two Pointers, Rotation | Rotated Sorted Array |
| 153 | M | Find Min in Rotated Sorted Array | Binary Search, Two Pointers, Rotation | Rotated Sorted Array |
| 154 | H | Find Min in Rotated Sorted Array 2 | Binary Search, Two Pointers, Rotation | Rotated Sorted Array |
| 11 | M | Container With Most Water | Two Pointers, Early Exit | - |
| 34 | M | Search For Range | Binary Search, Two Pointers, Sort | Search Range |
| 35 | M | Search Insert Position | Binary Search, Two Pointers | Search Range |
| 278 | E | First Bad Version | Binary Search | Search Range |
| 374 | E | Guess Number | Binary Search, Ternary Search | Search Range |
| 228 | M | Summary Range | Two Pointers, Int2Str | - |
| 268 | M | Missing Number | Bit Manipulation, Binary Search | - |
| 287 | M | Find Duplicate Number | Binary Search, Two Pointers, Hashtable, Value-as-Index, Sort | Cycle Detection |
2. hashtable
| # | *** | Name | Code Tags | Groups |
|---|---|---|---|---|
| 36 | E | Valid Sudoku | HashSet, Matrix Manipulation | - |
| 202 | E | Happy Number | HashSet, Two Pointers | - |
| 204 | E | Counting Prime | HashSet, Boolean Array, Math | - |
| 205 | E | Isomorphic String | HashMap, Value-As-Index | Mapping |
| 290 | E | Word Pattern | HashMap, String.split | Mapping |
| 242 | E | Valid Anagram | HashMap, Value-As-Index, Sort/Scan | Anagram |
| 49 | M | Group Anagrams | HashMap, String Sort | Anagram |
| 438 | E | Find Anagram In String | Slide Window, Two Pointers, Value-As-Index | Anagram |
| 246 | E | Strobogrammatic Number | HashMap, Two Pointers | - |
| 249 | E | Group Shifted String | HashMap, Math | - |
| 266 | E | Palindrome Permutation | HashSet, Coin-Flipping, Value-As-Index | Palindrome |
| 267 | M | Palindrome Permutation 2 | HashMap, Value-As-Index, Backtracking | Palindrome |
| 409 | E | Longest Palindrome | HashMap, Coin-Flipping, Value-As-Index | Palindrome |
| 288 | E | Unique Abbreviation | HashSet, HashMap | - |
| 299 | E | Bulls And Cows | Value-As-Index, Coin-Flipping | - |
| 349 | E | Intersection of Arrays | Sort, Two Pointers, Binary Search, HashSet | - |
| 350 | E | Intersection of Arrays 2 | Sort, HashMap | - |
| 359 | E | Logger Rate Limiter | HashMap | - |
| 389 | E | Find String Difference | HashMap, Bit Manipulation, Coin-Flipping | - |
| 3 | M | Longest Substring Without Repeating Characters | HashMap, Two Pointers, String Scan | - |
| 187 | M | Repeated DNA Sequences | HashMap, HashSet, Substring | - |
| 347 | M | Top K Frequent Element | Bucket, HashMap, Generic | Frequency |
| 451 | M | Sort Characters By Frequency | Bucket, HashMap, Value-As-Index | Frequency |
3. linkedlist
| # | *** | Name | Code Tags | Groups |
|---|---|---|---|---|
| 2 | E | Add Two Numbers | Dummy Node, Two Pointers, Sentinel, Math | Add Two Num |
| 445 | M | Add Two Numbers 2 | Tail Align, Dummy Node, Two Pointers, Sentinel | Add Two Num |
| 369 | M | Plus One (Linked List) | Recursion, Reverse, Two Pointers | Add Two Num |
| 19 | E | Remove Nth From End | Dummy Node, Recursion, Two Pointers | - |
| 21 | E | Merge Sorted Linked List | Dummy Node, Recursion, Sentinel | - |
| 24 | E | Swap Nodes in Pairs | Dummy Node, Tri-Pointers, Recursion | - |
| 83 | E | Remove Duplicate Nodes | Two Pointers, Recursion | Remove Nodes |
| 82 | M | Remove Duplicate Nodes 2 | Dummy Node, Two Pointers, Recursion | Remove Nodes |
| 203 | E | Remove Element | Node Delete, Dummy Node, Two Pointers | Remove Nodes |
| 237 | E | Delete Node | Node Delete | Remove Nodes |
| 141 | E | Linked List Cycle | Two Pointers, Floyd Loop Detection, HashSet | Cycle Detection |
| 142 | E | Linked List Cycle 2 | Two Pointers, Floyd Loop Detection, HashSet | Cycle Detection |
| 160 | E | Intersection of Linked List | Two Pointers, Loop Detection, Tail Align, HashSet | - |
| 206 | E | Reverse Linked List | Two Pointers, Dummy Node, Recursion | Linkedlist Reverse |
| 92 | M | Reverse Linked List 2 | Two Pointers, Dummy Node | Linkedlist Reverse |
| 234 | E | Palindrome Linked List | Two Pointers, Dummy Node, Recursion | Linkedlist Reverse |
| 143 | M | Reorder Linked List | Two Pointers, Reverse | Linkedlist Reverse |
| 61 | M | Rotate Linked List | Two Pointers, Loop | - |
| 147 | M | Implement Insertion Sort (Linked List) | Two Pointers, Dummy Node, Recursion | Sort |
| 148 | M | Implement Merge Sort (Linked List) | Two Pointers, Dummy Node Shift, Cut | Sort |
| 328 | M | Odd Even Linked List | Two Pointers, Dummy Node Shift | - |