Why? -> To reduce overthinking and avoiding anxiety & panic. -> Train the mind like training body. Problems -> Brain stuck in “what if” loops (future problems, alternate-case scenario...

Operation Availability By Collection Type ✅ - Available ❌ - Not Available 🔄 - Returns different type Operation List Set Map Array String Sequenc...

Quick Reference Tables Basic Operations Operation Description Example Returns filter Keep elements matching predicate list.filte...

A quick reference guide for length and size operations you’ll frequently need in competitive programming and problem-solving. Quick Reference Table Data Structure Property/Fu...

Quick reference for index operations commonly needed in problem-solving. Quick Reference Table Property/Function Applicable On Returns Example Notes ...

Problem Statement You are given an array prices where prices[i] represents the price of a given stock on the ith day. You want to maximize your profit by buying the stock on one day and selling it...

Collection Type Hierarchy Collection (Interface) ├── List (Interface) │ ├── ArrayList │ ├── LinkedList │ └── Arrays.asList() ├── Set (Interface) │ ├── HashSet │ ├── LinkedHashSet │ └──...

Problem Statement Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining. Solve Here: Trapping Rain Water ...

Problem Statement You are given an integer array height of length n, where each value represents the height of a vertical line drawn at that index. The task is to find two lines that, together wit...

Problem Statement Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that: i != j, i != k, and j != k nums[i] + nums[j] + nums[k] == 0 The solution set mu...