Introduction The “Valid Parentheses” problem (Leetcode 20) is a popular question often asked in coding interviews. The task is to check if a given string containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[‘ and ‘]’ is valid. An input string is valid if the brackets are correctly closed and nested. In this blog post, … Read more
Problem Description Given a linked list, remove nth node from end of list and return its head. The list can have various sizes, and the node we need to remove can be anywhere from the beginning to the end of the list. Approach To solve this problem efficiently, we need to think about how to … Read more
The 4Sum problem is a variation of the classic two-sum problem. The task is to find all unique quadruplets in an array that sum up to a target value. This problem is often encountered in coding interviews and algorithm competitions. In this blog post, we will discuss various solutions for the 4Sum problem, ranging from … Read more
The “Letter Combinations of a Phone Number“ problem is a classic question often asked in technical interviews. It challenges your understanding of backtracking, recursion, and efficient problem-solving. Let’s explore all possible solutions, from a naive approach to an optimized one, with their explanations, complexities, and Java implementations. Problem Statement for Letter Combinations of a Phone … Read more
The 3Sum Closest problem from Leetcode is a popular algorithmic challenge that tests your understanding of array manipulation and optimization techniques. In this article, we’ll cover the problem statement, a step-by-step approach to solving it, and explain multiple solutions from naive to optimized with their complexities. We’ll also provide well-commented Java code for each solution. … Read more
The 3Sum problem is a popular coding challenge on LeetCode that tests your ability to implement efficient algorithms for finding combinations. This blog will walk you through various approaches, from the brute force method to optimized solutions, with complete explanations, time complexities, and Java implementations. Problem Statement 3Sum: Given an integer array nums, return all … Read more
The Longest Common Prefix problem on Leetcode is a classic string manipulation problem. Here’s the problem statement: Problem Statement: Write a function to find the longest common prefix string amongst an array of strings.If there is no common prefix, return an empty string “”. Examples: Example 1: Example 2: Naive Solution: Compare Characters Iteratively Approach: … Read more
The “Roman to Integer” problem, Leetcode problem #13, is a classic interview question that tests your understanding of algorithms and data structures. In this problem, you’re tasked with converting a given Roman numeral string to an integer. Problem Description Roman numerals are represented by seven different symbols: For example: The challenge is to convert a … Read more
Converting an integer to a Roman numeral is a common problem in coding interviews and algorithm challenges. In this blog post, we will explore the Leetcode 12: Integer to Roman problem, explain various approaches, and provide Java code solutions for each method. Problem Statement for Integer to Roman Given an integer num, convert it into … Read more
Palindromes are fascinating sequences that read the same backward as forward. In computer science, one popular problem is identifying the longest palindromic substring within a given string. While a brute-force approach may work, it often lacks efficiency, especially for long strings. That’s where Manacher’s Algorithm shines, offering a linear time complexity solution. Let’s dive deep … Read more