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LeetCode Study Note | Problem 198: House Robber

2025-05-18

LeetCode #Dynamic Programming#Array
🏠 Problem Overview You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, but adjacen
LeetCode Study Note | Problem 207: Course Schedule

2025-05-17

LeetCode #Graph#Breadth-First Search# Depth-First Search# Topological Sort
Problem Summary You are given numCourses courses labeled from 0 to numCourses - 1, and a list of prerequisites where each element is a pair [a, b] mea
LeetCode Study Note | Problem 994: Rotting Oranges

2025-05-17

LeetCode #Array#Breadth-First Search#Matrix
🔍 Problem Overview You’re given an m x n grid, where: 0 represents an empty cell 1 represents a fresh orange 2 represents a rotten orange Each minute
LeetCode Study Note | Problem 200: Number of Islands

2025-05-17

LeetCode #Array# Depth-First Search#Breadth-First Search#Matrix#Union Find
🌊 Problem Summary You are given a 2D grid consisting of '1's (land) and '0's (water). An island is formed by connecting adjacent lands horizontally o
LeetCode Study Note | Problem 15: 3Sum

2025-05-15

LeetCode #Array#Two Pointers#Sorting
✨ Problem Description Given an integer array nums, return all the unique triplets [nums[i], nums[j], nums[k]] such that i ≠ j ≠ k, and nums[i] + nums[
LeetCode Study Note | Problem 283: Move Zeroes

2025-05-15

LeetCode #Two Pointers#Array
🧩 Problem Description Given an integer array nums, move all 0’s to the end of it while maintaining the relative order of the non-zero elements. Examp
LeetCode Study Note | Problem 128: Longest Consecutive Sequence

2025-05-13

LeetCode #Array#Hash Table#Union Find
📌 Problem Summary Given an unsorted array of integers, find the length of the longest consecutive elements sequence. Time complexity must be O(n). Ex
LeetCode Study Note | Problem 49: Group Anagrams

2025-05-13

LeetCode #Array#Hash Table#String#Sorting
🧩 Problem Summary Given an array of strings, group the anagrams together. Anagram: A word formed by rearranging the letters of another word (e.g., "e
LeetCode Study Note | Problem 2: Add Two Numbers

2025-05-12

LeetCode #Linked List#Math#Recursion
🧠 Problem Summary Given two non-empty linked lists representing two non-negative integers in reverse order (each node contains a single digit), retur
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