| # | Title | Solution | Tutorial | Level | Remarks | | --- | --- | --- | --- | --- | --- | |01| 1. Two Sum| Python, Swift | --- | --- | ✅ 📌 ⭐ 😭 🧐 😎 | |02| 485. Max Consecutive Ones| Swift| |03| 476. Number Complement| Swift| |04| 461. Hamming Distance| Swift| |05| 9. Palindrome Number| Python| |06| 88. Merge Sorted Array| Python| |07| 811. Subdomain Visit Count| Python| |08| 771. Jewels and Stones| Python| |09| 414. Third Maximum Number| Python| |10| 259. 3Sum Smaller| Python| |11| 16. 3Sum Closest| Python| |12| 15. 3Sum| Python| |13| 118. Pascal's Triangle| Python| |14| 119. Pascal's Triangle II| Python| |15| 238. Product of Array Except Self| Python, Swift | |16| 724. Find Pivot Index| Python| | |17| 747. Largest Number At Least Twice of Others| Python| | |18| 581. Shortest Unsorted Continuous Subarray| Python| | |19| 904. Fruit Into Baskets| Python| Article, Video 1, Video 2| Medium | Sliding Window, Two Pointer | |20| 56. Merge Intervals| Python| Article, Swift | |21| 334. Increasing Triplet Subsequence| Python| --- | Medium | --- | |22| 792. Number of Matching Subsequences| Python| Official | Medium | Very tricky. Check again | |23| 912. Sort an Array (Merge Sort)| Python.py)|--- | Medium | --- | |24| 1118. Number of Days in a Month| Python|--- | Easy | --- | |25| 349. Intersection of Two Arrays| Python| Art 1, Art 2 | Easy | Very tricky and versatile | |26| 350. Intersection of Two Arrays II| Python| [](), [](), []() | Easy | Very tricky and versatile | |27| 303. Range Sum Query - Immutable| Python| Vid 1 | Easy | --- | |28| 560. Subarray Sum Equals K| Python, Swift | Art 1, Art 2, Art 3, Art 4, Art 5, Art 6 | Medium | Very tricky and persuasive with Sliding Window but it's not. This is a classic running sum problem | |29| 325. Maximum Size Subarray Sum Equals k| Python| Art 1 | Medium | Very tricky and persuasive with Sliding Window but it's not. This is a classic running sum problem | |30| 1074. Number of Submatrices That Sum to Target| Python| Art 1, Art 2, Art 3, Art 4 | Extremely Hard | Very tricky and hard, check again. Also DP | |31| 167. Two Sum II - Input array is sorted| Python| --- | Easy | Two pointer basics | |32| 1099. Two Sum Less Than K| Python| --- | Easy | Two pointer basics | |33| 26. Remove Duplicates from Sorted Array| Python| --- | Easy | Two pointer basics | |34| 977. Squares of a Sorted Array| Python| --- | Easy | Two pointer basics | |35| 713. Subarray Product Less Than K| Python| --- | Medium | Two pointer ad Sliding Window | |36| 75. Sort Colors| Python| Vid 1 | Medium | Two pointer | |37| 18. 4Sum| Python| --- | Medium | Two pointer | |38| 11. Container With Most Water| Python| --- | Medium | Two pointer | |39| 202. Happy Number| Python| Art 1 | Easy | Fast pointer Slow pointer | |40| 457. Circular Array Loop| Python| --- | Medium | Fast pointer Slow pointer. Check again | |41| 448. Find All Numbers Disappeared in an Array| Python| --- | Easy | Cyclic Sort | |42| 287. Find the Duplicate Number| Python| --- | Medium | Cyclic Sort. TODO: Check all other approaches | |43| 442. Find All Duplicates in an Array| Python| --- | Medium | Cyclic Sort TODO: Check all other approaches | |44| 41. First Missing Positive| Python| --- | Hard | Cyclic Sort, Very important | |45| 939. Minimum Area Rectangle | Python| Art 1 | Medium | Hash and Set, Very important | |46| 359. Logger Rate Limiter | Python| --- | Easy | Hash and Set, Very important | |47| 48. Rotate Image | Python| Must, Vid 1 | Medium | Very important | |48| 362. Design Hit Counter | Python, Swift| --- | Medium | --- | |49| 289. Game of Life | Python, Swift| --- | Medium | --- | |50| 54. Spiral Matrix | Python, Swift| Official, Algoexpert.io | Medium | --- | |51| 380. Insert Delete GetRandom O(1) | Python.py), Swift.swift)| Official | Medium | --- | |52| 835. Image Overlap | Python, Swift| Art 1, Art 2 | Medium | --- | |53| 1051. Height Checker | Python, Swift | --- | Easy | | |55| 683. K Empty Slots | Python, Swift | Art 1, Art 2, Art 3 | Hard | TODO: Check monotonic queue approach. Solved it with sliding widow | |56| 849. Maximize Distance to Closest Person | Python, Swift | Art 1 | Easy | Not so easy and intuitive. Can be solve is a variety of way. I have used Binary search(A bit over engineered solution). Can be simplifies | |57| 283. Move Zeroes | Python, Swift | --- | Easy | Not so easy and intuitive. Uses fast and slow pointer | |58| 163. Missing Ranges | Python, Swift | --- | Medium | Man, it's a very trick problem | |59| 1089. Duplicate Zeros | Python, Swift | Art 1 | Easy | Not so easy and intuitive. Check again | |60| 941. Valid Mountain Array | Python, Swift | | Easy | | |61| 731. My Calendar II | Python, Swift | | Medium | Merge interval | |62| 59. Spiral Matrix II | Python, Swift | | Medium | loved it | |63| 525. Contiguous Array | Python, Swift | Art 1 | Medium | loved it. Check again | |64| 379. Design Phone Directory | Python, Swift | | Medium | | |65| 280. Wiggle Sort | Python, Swift | | Medium | | |66| 246. Strobogrammatic Number | Python, Swift | | Easy | | |67| 845. Longest Mountain in Array | Python, Swift | | Medium | | |68| 66. Plus One | Python, Swift | | Easy | | |69| 957. Prison Cells After N Days | Python, Swift | Art 1, Art 2, Art 3, Art 4, Art 5 | Medium | | |70| 1232. Check If It Is a Straight Line | Python, Swift | | Easy | | |71| 348. Design Tic-Tac-Toe | Python, Swift | Vid 1, Art 1 | Medium | A fucking tricky question | |72| 1152. Analyze User Website Visit Pattern | Python, Swift | Art 1, Art 2, Art 3, Art 4 | Medium | A fucking unclear question and problem. I Fucking disliked it. | |73| 953. Verifying an Alien Dictionary | Python, Swift | | Easy(REALLY!!!) | Don't be fooled by the difficulty label | |74| 463. Island Perimeter | Python, Swift | | Easy | It's very deceiving, to think it as a grapy ad DFS problem, but it's not. Think simply | |75| 166. Fraction to Recurring Decimal | Python, Swift | Art 1 | Medium | Hate this problem. Why do companies ask this shit!!! | |75| 311. Sparse Matrix Multiplication | Python, Swift | Art 1, Art 2, Art 3, Art 4 | Medium | Very tricky | |76| 896. Monotonic Array | Python, Swift | --- | Eassy | | |77| 670. Maximum Swap | Python, Swift | Art 1 | Medium | | |78| 825. Friends Of Appropriate Ages | Python, Swift | Art 1 | Medium | Think differently from a different angle. Loved this problem | |79| 189. Rotate Array | Python, Swift | --- | Easy | Getting to inplace (O(n) time and O(1) space) solution is tricky. | |80| 1004. Max Consecutive Ones III | Python, Swift | --- | Medium | Solution is tricky. | |81| 498. Diagonal Traverse | Python, Swift | --- | Medium | --- | |82| 766. Toeplitz Matrix | Python, Swift | --- | Easy | --- | |83| 1031. Maximum Sum of Two Non-Overlapping Subarrays | Python, Swift | --- | Medium | PrefixSum | |84| 1438. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit | Python, Swift | (Art 1)[https://tinyurl.com/y69hjhjp], (Art 2)[https://tinyurl.com/y3h2fj2m] | Medium | Sliding window | |85| 1428. Leftmost Column with at Least a One | Python, Swift | --- | Medium | Binary Search | |86| 914. X of a Kind in a Deck of Cards | Python, Swift | --- | Easy (Not So) | | |87| 1275. Find Winner on a Tic Tac Toe Game | Python, Swift | Art 1 | Easy (Not So) | | |88| 532. K-diff Pairs in an Array | Python, Swift | Art 1 | Medium | | |89| 128. Longest Consecutive Sequence | Python, Swift | Art 1 | Hard | | |90| 1423. Maximum Points You Can Obtain from Cards | Python, Swift | Art 1, Art 2 | Medium | Very important. Learned new ways of sliding window | |91| 900. RLE Iterator | Python, Swift | --- | Medium | - | |92| 954. Array of Doubled Pairs | Swift | --- | Medium | - | |93| 853. Car Fleet | Swift | Vid 1, Art 1 ] | Medium | - | |94| 1877. Minimize Maximum Pair Sum in Array | Swift | Art 1 ] | Medium | - |

| # | Title | Solution | Tutorial | Level | Remarks | | --- | --- | --- | --- | --- | --- | |01| 3. Longest Substring Without Repeating Characters| | |02| 412. Fizz Buzz| Swift| |03| 937. Reorder Log Files| Python| |03| 929. Unique Email Addresses| Python| |04| 7. Reverse Integer| Python| |05| 13. Roman to Integer| Python| |06| 125. Valid Palindrome| Python, Swift | |07| 161. One Edit Distance| Python| |08| 1119. Remove Vowels from a String| Python| |09| 344. Reverse String| Python| |10| 482. License Key Formatting| Python| | |11| 3. Longest Substring Without Repeating Characters| Python| Vid 1, Vid 2 | Medium | 📌 Sliding window, Two pointer | |12| 340. Longest Substring with At Most K Distinct Characters| Python, Swift | Vid 1, Art 1, Art 2 | Hard | 📌 Sliding window, Two pointer | |13| 159. Longest Substring with At Most Two Distinct Characters| Python| Vid 1 | Hard | 📌 Sliding window, Two pointer | |14| 424. Longest Repeating Character Replacement| Python| Vid 1, Vid 2, Art 1, Art 2, Art 3, Art 4 | Medium | 📌 Sliding window, Very important | |15| 76. Minimum Window Substring | Python| Vid 1, Vid 2, Vid 3 | Hard | 📌 Sliding window, Very important | |16| 727. Minimum Window Subsequence| Python| Vid 1, Art 1, Art 2 | Hard | 📌 Sliding window and DP, check the DP approach | |17| 438. Find All Anagrams in a String| Python, Swift | Must, Art 1 | Medium | 📌 Sliding window | |18| 567. Permutation in String| Python| Must | Medium | 📌 Sliding window | |19| 844. Backspace String Compare| Python| --- | Easy | 📌 Two Pointer | |20| 809. Expressive Words| Python| Art 1 | Medium | 📌 Logic ad analytical prolem | |21| 271. Encode and Decode Strings| Python| Art 1 | Medium | 📌 TODO: Check the second approach. Very Important | |22| 299. Bulls and Cows| Python| --- | Easy | --- | |23| 833. Find And Replace in String| Python| Art 1 | Medium | --- | |24| 49. Group Anagrams| Python| Art 1, Algoexpert.io | Medium | --- | |25| 551. Student Attendance Record I| Python| | Easy | --- | |26| 242. Valid Anagram| Python, Swift | | Easy | --- | |27| 1358. Number of Substrings Containing All Three Characters| Python, Swift | Art 1 | Medium | Sliding Window | |28| 459. Repeated Substring Pattern | Python, Swift | Art 1 | Easy | I fucking love this problem | |29| 681. Next Closest Time | Python, Swift | Art 1 | Medium | I feel stupid after trying my first solution | |30| 925. Long Pressed Name | Python, Swift | --- | Easy | | |31| 949. Largest Time for Given Digits | Python, Swift | --- | Easy | Not so easy | |32| 788. Rotated Digits | Python, Swift | --- | Easy | --- | |33| 388. Longest Absolute File Path | Python, Swift | --- | Medium | --- | |34| 616. Add Bold Tag in String | Python, Swift | --- | Medium | Merge intervals(hidden) | |35| 678. Valid Parenthesis String | Python, Swift | Art 1, Art 2, Art 3, Art 4 | Medium | Super tricky. Much check again | |36| 273. Integer to English Words | Python, Swift | | Hard | MUST check again | |37| 763. Partition Labels | Python, Swift | | Medium | | |38| 819. Most Common Word | Python, Swift | Art 1 | Easy | | |39| 350. Intersection of Two Arrays II | Python, Swift | --- | Easy | Check the follow-ups | |40| 249. Group Shifted Strings | Python, Swift | Art 1 | Medium | Tricky one | |41| 158. Read N Characters Given Read4 II - Call multiple times | Python, Swift | Art 1 | Hard | Good one | |42| 415. Add Strings | Python, Swift | Art 1 | Easy | --- | |43| 65. Valid Number | Python, Swift | Art 1 | HARD | A fucking difficult but important problem. Chack DFA approach | |44| 791. Custom Sort String | Python, Swift | --- | Medium | Loved this problem | |45| 157. Read N Characters Given Read4 | Python, Swift | --- | Easy (Not So!) | Loved this problem | |46| 722. Remove Comments | Python, Swift | Art 1 | Medium | | |47| 443. String Compression | Python, Swift | Art 1 | Medium | | |48| 1525NumberofGoodWaystoSplitaString | Swift | --- | Medium | | |48| 2007FindOriginalArrayFromDoubledArray | Swift | --- | Medium | |