Two Pointers Technique in Java — A Practical Guide for Serious Engineers
Two Pointers is one of the most effective techniques for turning brute-force array/string solutions into linear-time solutions.
DSA
Sort Array by Parity in Java
This guide explains the intuition, optimized approach, and Java implementation for sort array by parity in java, with practical tips for interviews and produ...
Maximum Subarray in Java (Kadane Algorithm)
This guide explains the intuition, optimized approach, and Java implementation for maximum subarray in java (kadane algorithm), with practical tips for inter...
Valid Parentheses in Java
Given a string containing only ()[]{}, return true if brackets are valid. A valid string must close in correct order and with correct bracket type.
Find All Numbers Disappeared in an Array in Java
Given an array nums of size n where values are in range [1, n], some numbers appear twice and others are missing. Return all missing numbers.
Move Zeroes in Java (Stable In-Place)
This guide explains the intuition, optimized approach, and Java implementation for move zeroes in java (stable in-place), with practical tips for interviews ...
Single Number in Java Using XOR
Given an integer array where every value appears exactly twice except one value, return the value that appears once.
Maximum Depth of Binary Tree in Java
This guide explains the intuition, optimized approach, and Java implementation for maximum depth of binary tree in java, with practical tips for interviews a...
Remove Duplicates from Sorted List II in Java
This guide explains the intuition, optimized approach, and Java implementation for remove duplicates from sorted list ii in java, with practical tips for int...
Remove Duplicates from Sorted Array in Java
Given a sorted array, remove duplicates in-place so each unique value appears once. Return the number of unique elements.
Remove All Adjacent Duplicates in String (Java)
Given a string, repeatedly remove adjacent equal characters until no such pair remains.
Palindrome Number in Java (Without String Conversion)
This guide explains the intuition, optimized approach, and Java implementation for palindrome number in java (without string conversion), with practical tips...
Middle of the Linked List in Java
Given the head of a singly linked list, return its middle node. If the list has two middle nodes, return the second middle.
Longest Substring Without Repeating Characters in Java
This guide explains the intuition, optimized approach, and Java implementation for longest substring without repeating characters in java, with practical tip...
Linked List Cycle II in Java (Find Cycle Start)
This guide explains the intuition, optimized approach, and Java implementation for linked list cycle ii in java (find cycle start), with practical tips for i...
First Missing Positive in Java
This guide explains the intuition, optimized approach, and Java implementation for first missing positive in java, with practical tips for interviews and pro...
Find First and Last Position of Element in Sorted Array
This guide explains the intuition, optimized approach, and Java implementation for find first and last position of element in sorted array, with practical ti...
Find Minimum in Rotated Sorted Array in Java
Given a rotated sorted array with distinct values, find the minimum element in O(log n).
Remove Linked List Elements in Java
This guide explains the intuition, optimized approach, and Java implementation for remove linked list elements in java, with practical tips for interviews an...
Remove Duplicates from Sorted List (LeetCode 83)
Given a sorted linked list, remove duplicate nodes so each value appears exactly once.
Container With Most Water in Java
Given an array height, pick two indices i and j to form a container. Maximize area:
Binary Search in Java (Iterative and Recursive)
This guide explains the intuition, optimized approach, and Java implementation for binary search in java (iterative and recursive), with practical tips for i...
Add Two Numbers Represented as Linked List
This guide explains the intuition, optimized approach, and Java implementation for add two numbers represented as linked list, with practical tips for interv...
Detect a Loop in Linked List (Floyd Cycle Detection)
This guide explains the intuition, optimized approach, and Java implementation for detect a loop in linked list (floyd cycle detection), with practical tips ...
Reverse Linked List Recursively in Java
Reverse a singly linked list using recursion.
Reverse Linked List Iteratively in Java
This guide explains the intuition, optimized approach, and Java implementation for reverse linked list iteratively in java, with practical tips for interview...