📌 Problem Summary Given an unsorted array of integers, find the length of the longest consecutive elements sequence. Time complexity must be O(n). Ex
🧩 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
🧠 Problem Summary Given two non-empty linked lists representing two non-negative integers in reverse order (each node contains a single digit), retur
🔍 Problem Description Given a non-negative integer array height[] representing the elevation map where the width of each bar is 1, compute how much w
Problem Overview Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its s
Problem Overview Given a string s, find the length of the longest substring without repeating characters. Example： Input: "abcabcbb" Output: 3 Explana
