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  01: Introduction What is the Minimum Window Substring Problem? Minimum Window Substring is one of those problems that shows up in almost every coding interview. At first glance it looks a bit tricky, but once you understand the sliding window technique behind it, the whole thing clicks into place. The basic idea is simple: … Read more

  📋 Table of Contents Introduction Problem Statement Input & Output Format Flowchart Pseudocode Python Program Program Explanation Time & Space Complexity Test Cases Common Interview Questions Conclusion FAQs 01: Introduction If you are learning Data Structures and Algorithms (DSA), you will almost certainly come across the problem — Longest Substring Without Repeating Characters. It … Read more

01: Introduction Strings are everywhere in programming — names, passwords, messages, URLs. And one of the most common string problems you will face, both in interviews and real coding tasks, is finding the first non-repeating character in a string. So what does that mean? Let’s say you have the word “programming”. Some characters appear more … Read more

01: Introduction Have you ever noticed that the word “listen” and the word “silent” use the exact same letters? That is what an anagram is — two words or strings that contain the same characters but arranged in a different order. For example, “triangle” and “integral” are anagrams. So are “eat” and “tea”. The letters … Read more

01: Introduction Checking if a string is a palindrome in Python is one of the most common — words like madam, racecar, level, and civic are all palindromes. They read the same whether you go left to right or right to left. Checking if a string is a palindrome in Python is one of the … Read more

  One of the most frequently asked array problems in coding interviews. Beginner-friendly breakdown with Python code, dry run, visualization, and everything you need to crack it in an interview. To find the longest subarray with sum K, use a prefix sum with a HashMap. As you traverse the array, compute the running sum. If … Read more

01: Introduction Imagine you get your monthly bank statement. You want to find if there was any period of days where your spending added up to exactly ₹12,000. Going through every possible combination of days manually is exhausting — and in code, that’s exactly what a brute force O(n²) solution does.The Subarray with Given Sum … Read more

01: Introduction The Product of Array Except Self is one of those problems that looks simple on the surface but catches most beginners completely off guard — especially in live interviews. You are given an integer array and you need to return a new array where every position holds the product of all elements except … Read more

01: Introduction Imagine you could see Apple’s stock prices for the past week — $180, $140, $155, $130, $170, $160. You can buy once and sell once. Which days do you pick to make the most money? This is the Best Time to Buy and Sell Stock problem — one of the most commonly asked … Read more

01: Introduction The majority element in an array is the element that appears more than n/2 times. The fastest way to find it is the Boyer-Moore Voting Algorithm, which runs in O(n) time and uses O(1) space — making it the go-to solution in coding interviews.The majority element problem shows up constantly in coding interviews … Read more