LeetCode - Starting Again Day 2

🧩 Problem 1

Title : Two Sum
Difficulty : Easy
Topic : Arrays, HashMap
Tags : #arrays #hashmap #twopointer #leetcodeeasy
Description :
Given an array of integers and a target value, return the indices of the two numbers that add up to the target. This is a classic beginner-friendly problem that helps build intuition around hashing and lookup operations. Focus on time complexity optimization using hash maps.
Link : https://leetcode.com/problems/two-sum

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🧩 Problem 2

Title : Reverse String
Difficulty : Easy
Topic : Strings, Two Pointers
Tags : #string #twopointer #inplace #leetcodeeasy
Description :
You’re given a character array. Reverse the characters in-place without using any extra space. Mastering this improves understanding of two-pointer technique and memory-efficient solutions. Commonly asked in beginner interviews to test low-level string manipulation.
Link : https://leetcode.com/problems/reverse-string

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🧩 Problem 3

Title : Merge Two Sorted Lists
Difficulty : Easy
Topic : Linked List, Recursion
Tags : #linkedlist #recursion #sorting #leetcodeeasy
Description :
Merge two sorted linked lists and return the result as a new sorted list. Helps develop recursion-based thinking and understanding of linked list node manipulation. Also teachable using iterative methods for comparison. Link : [https://leetcode.com/problems/merge-two-sorted-lists] (https://leetcode.com/problems/merge-two-sorted-lists)

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🧩 Problem 4

Title : Valid Parentheses
Difficulty : Easy
Topic : Stack, String
Tags : #stack #string #validbrackets #leetcodeeasy
Description :
Determine if an input string of brackets is valid — every open bracket must be closed in the correct order. Excellent introduction to stack-based parsing logic and balancing expressions. Frequently asked to test candidate's approach to handling edge cases and nested patterns. Link : https://leetcode.com/problems/valid-parentheses

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🧩 Problem 5

Title : Maximum Depth of Binary Tree Difficulty : Easy
Topic : Trees, DFS, Recursion
Tags : #tree #dfs #recursion #binarytree #leetcodeeasy
Description :
Find the maximum depth (height) of a binary tree.
Teaches how to explore tree nodes recursively using Depth-First Search (DFS). An essential problem for understanding the basics of tree traversal. Link : [https://leetcode.com/problems/maximum-depth-of-binary-tree] (https://leetcode.com/problems/maximum-depth-of-binary-tree)