Welcome to Arrays And Strings CodeSnap

The 'Arrays & Strings' category forms the backbone of most technical coding interviews and real-world applications. These problems test your ability to manipulate sequences of data, handle edge cases efficiently, and write optimized code. From searching for patterns in strings to modifying arrays in-place, you'll learn essential techniques like two-pointer strategies, sliding window algorithms, hash-based lookups, and binary search. Mastery here strengthens your grasp on both fundamental and advanced data manipulation skills.

Table of Contents

• Valid Subsequence Checker

  Given two arrays, determine if the second array is a valid subsequence of the first. A subsequence maintains the relative order of elements but doesn't require contiguity.

• Remove Duplicates from Sorted Array

  Given a sorted array, remove duplicates in-place so that each element appears only once. Return the new length of the array after removing duplicates, ensuring constant space usage.

• Longest Substring Without Repeating Characters

  Find the length of the longest substring in a given string that contains no repeating characters. Use a sliding window approach and hash structures to efficiently track character occurrences.

• Reverse Words in a String

  Given a string, reverse the order of words. Trim extra spaces and ensure that words are separated by a single space with no leading or trailing spaces in the final result.

• Find First and Last Position of Element

  Given a sorted array and a target value, return the indices of the first and last occurrence of the target. If the target is not found, return [-1, -1]. Use binary search to achieve logarithmic time complexity.

• Two Sum

  Given an array of integers nums and an integer target, return the indices of the two numbers such that they add up to target. Use a hash map for constant time lookups to achieve linear time complexity.