Learning

Skills I am practising alongside my projects, and how far along I am.

DSA: NeetCode 150

150 coding problems covering the common patterns in technical interviews. This section reads from the spreadsheet I track them in, so it is always up to date. Each solved problem has a one-line note on its key idea, in my own words.

– of 150 solved

Easy: – / 28
Medium: – / 101
Hard: – / 21
Revisited: –

Started 10 October 2026

All problems

In study order

Arrays & Hashing9

Not started:
Contains Duplicate on LeetCodeEasy
Not started:
Valid Anagram on LeetCodeEasy
Not started:
Two Sum on LeetCodeEasy
Not started:
Group Anagrams on LeetCodeMedium
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Top K Frequent Elements on LeetCodeMedium
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Encode and Decode Strings on LeetCodeMedium
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Product of Array Except Self on LeetCodeMedium
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Valid Sudoku on LeetCodeMedium
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Longest Consecutive Sequence on LeetCodeMedium

Two Pointers5

Not started:
Valid Palindrome on LeetCodeEasy
Not started:
Two Sum II Input Array Is Sorted on LeetCodeMedium
Not started:
3Sum on LeetCodeMedium
Not started:
Container With Most Water on LeetCodeMedium
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Trapping Rain Water on LeetCodeHard

Sliding Window6

Not started:
Best Time to Buy and Sell Stock on LeetCodeEasy
Not started:
Longest Substring Without Repeating Characters on LeetCodeMedium
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Longest Repeating Character Replacement on LeetCodeMedium
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Permutation in String on LeetCodeMedium
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Minimum Window Substring on LeetCodeHard
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Sliding Window Maximum on LeetCodeHard

Stack7

Not started:
Valid Parentheses on LeetCodeEasy
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Min Stack on LeetCodeMedium
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Evaluate Reverse Polish Notation on LeetCodeMedium
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Generate Parentheses on LeetCodeMedium
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Daily Temperatures on LeetCodeMedium
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Car Fleet on LeetCodeMedium
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Largest Rectangle in Histogram on LeetCodeHard

Binary Search7

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Binary Search on LeetCodeEasy
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Search a 2D Matrix on LeetCodeMedium
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Koko Eating Bananas on LeetCodeMedium
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Find Minimum in Rotated Sorted Array on LeetCodeMedium
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Search in Rotated Sorted Array on LeetCodeMedium
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Time Based Key-Value Store on LeetCodeMedium
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Median of Two Sorted Arrays on LeetCodeHard

Linked List11

Not started:
Reverse Linked List on LeetCodeEasy
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Merge Two Sorted Lists on LeetCodeEasy
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Linked List Cycle on LeetCodeEasy
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Reorder List on LeetCodeMedium
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Remove Nth Node From End of List on LeetCodeMedium
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Copy List With Random Pointer on LeetCodeMedium
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Add Two Numbers on LeetCodeMedium
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Find the Duplicate Number on LeetCodeMedium
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LRU Cache on LeetCodeMedium
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Merge K Sorted Lists on LeetCodeHard
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Reverse Nodes in K-Group on LeetCodeHard

Trees15

Not started:
Invert Binary Tree on LeetCodeEasy
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Maximum Depth of Binary Tree on LeetCodeEasy
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Diameter of Binary Tree on LeetCodeEasy
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Balanced Binary Tree on LeetCodeEasy
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Same Tree on LeetCodeEasy
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Subtree of Another Tree on LeetCodeEasy
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Lowest Common Ancestor of a Binary Search Tree on LeetCodeMedium
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Binary Tree Level Order Traversal on LeetCodeMedium
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Binary Tree Right Side View on LeetCodeMedium
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Count Good Nodes in Binary Tree on LeetCodeMedium
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Validate Binary Search Tree on LeetCodeMedium
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Kth Smallest Element in a BST on LeetCodeMedium
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Construct Binary Tree from Preorder and Inorder Traversal on LeetCodeMedium
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Binary Tree Maximum Path Sum on LeetCodeHard
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Serialize and Deserialize Binary Tree on LeetCodeHard

Tries3

Not started:
Implement Trie (Prefix Tree) on LeetCodeMedium
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Design Add and Search Words Data Structure on LeetCodeMedium
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Word Search II on LeetCodeHard

Heap / Priority Queue7

Not started:
Kth Largest Element in a Stream on LeetCodeEasy
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Last Stone Weight on LeetCodeEasy
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K Closest Points to Origin on LeetCodeMedium
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Kth Largest Element in an Array on LeetCodeMedium
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Task Scheduler on LeetCodeMedium
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Design Twitter on LeetCodeMedium
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Find Median from Data Stream on LeetCodeHard

Backtracking9

Not started:
Subsets on LeetCodeMedium
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Combination Sum on LeetCodeMedium
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Permutations on LeetCodeMedium
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Subsets II on LeetCodeMedium
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Combination Sum II on LeetCodeMedium
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Word Search on LeetCodeMedium
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Palindrome Partitioning on LeetCodeMedium
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Letter Combinations of a Phone Number on LeetCodeMedium
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N-Queens on LeetCodeHard

Graphs13

Not started:
Number of Islands on LeetCodeMedium
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Max Area of Island on LeetCodeMedium
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Clone Graph on LeetCodeMedium
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Walls and Gates on LeetCodeMedium
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Rotting Oranges on LeetCodeMedium
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Pacific Atlantic Water Flow on LeetCodeMedium
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Surrounded Regions on LeetCodeMedium
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Course Schedule on LeetCodeMedium
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Course Schedule II on LeetCodeMedium
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Graph Valid Tree on LeetCodeMedium
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Number of Connected Components in an Undirected Graph on LeetCodeMedium
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Redundant Connection on LeetCodeMedium
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Word Ladder on LeetCodeHard

Advanced Graphs6

Not started:
Reconstruct Itinerary on LeetCodeHard
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Min Cost to Connect All Points on LeetCodeMedium
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Network Delay Time on LeetCodeMedium
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Swim in Rising Water on LeetCodeHard
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Alien Dictionary on LeetCodeHard
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Cheapest Flights Within K Stops on LeetCodeMedium

1-D Dynamic Programming12

Not started:
Climbing Stairs on LeetCodeEasy
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Min Cost Climbing Stairs on LeetCodeEasy
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House Robber on LeetCodeMedium
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House Robber II on LeetCodeMedium
Not started:
Longest Palindromic Substring on LeetCodeMedium
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Palindromic Substrings on LeetCodeMedium
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Decode Ways on LeetCodeMedium
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Coin Change on LeetCodeMedium
Not started:
Maximum Product Subarray on LeetCodeMedium
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Word Break on LeetCodeMedium
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Longest Increasing Subsequence on LeetCodeMedium
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Partition Equal Subset Sum on LeetCodeMedium

2-D Dynamic Programming11

Not started:
Unique Paths on LeetCodeMedium
Not started:
Longest Common Subsequence on LeetCodeMedium
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Best Time to Buy and Sell Stock with Cooldown on LeetCodeMedium
Not started:
Coin Change II on LeetCodeMedium
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Target Sum on LeetCodeMedium
Not started:
Interleaving String on LeetCodeMedium
Not started:
Longest Increasing Path in a Matrix on LeetCodeHard
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Distinct Subsequences on LeetCodeHard
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Edit Distance on LeetCodeMedium
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Burst Balloons on LeetCodeHard
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Regular Expression Matching on LeetCodeHard

Greedy8

Not started:
Maximum Subarray on LeetCodeMedium
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Jump Game on LeetCodeMedium
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Jump Game II on LeetCodeMedium
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Gas Station on LeetCodeMedium
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Hand of Straights on LeetCodeMedium
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Merge Triplets to Form Target Triplet on LeetCodeMedium
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Partition Labels on LeetCodeMedium
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Valid Parenthesis String on LeetCodeMedium

Intervals6

Not started:
Insert Interval on LeetCodeMedium
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Merge Intervals on LeetCodeMedium
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Non-overlapping Intervals on LeetCodeMedium
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Meeting Rooms on LeetCodeEasy
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Meeting Rooms II on LeetCodeMedium
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Minimum Interval to Include Each Query on LeetCodeHard

Math & Geometry8

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Rotate Image on LeetCodeMedium
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Spiral Matrix on LeetCodeMedium
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Set Matrix Zeroes on LeetCodeMedium
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Happy Number on LeetCodeEasy
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Plus One on LeetCodeEasy
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Pow(x, n) on LeetCodeMedium
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Multiply Strings on LeetCodeMedium
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Detect Squares on LeetCodeMedium

Bit Manipulation7

Not started:
Single Number on LeetCodeEasy
Not started:
Number of 1 Bits on LeetCodeEasy
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Counting Bits on LeetCodeEasy
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Reverse Bits on LeetCodeEasy
Not started:
Missing Number on LeetCodeEasy
Not started:
Sum of Two Integers on LeetCodeMedium
Not started:
Reverse Integer on LeetCodeMedium