Easy LeetCode problems

Two Sum

Two Sum is solved fastest by storing seen values in a hash map and checking each number's needed complement once.

Palindrome Number

Determine if a given integer reads the same forward and backward using a math-driven solution strategy without convertin…

Roman to Integer

Convert a Roman numeral string into an integer using a hash table and mathematical principles to determine value order.

Longest Common Prefix

Find the longest common prefix in an array of strings, returning an empty string if none exists.

Valid Parentheses

Determine if a string of parentheses, brackets, and braces is correctly nested using a stack for proper order validation…

Merge Two Sorted Lists

Merge two sorted linked lists by splicing nodes into one sorted list using linked-list pointer manipulation and recursio…

Remove Duplicates from Sorted Array

Learn how to remove duplicates from a sorted array in-place using two-pointer scanning while preserving element order.

Remove Element

Remove Element challenges you to remove a value from an array in-place using efficient two-pointer scanning and tracking…

Find the Index of the First Occurrence in a String

Locate the first occurrence of a substring within a string using a two-pointer scanning strategy and invariant tracking …

Search Insert Position

Find the correct index for a target value in a sorted array using binary search, or return the position where it should …

Length of Last Word

Determine the length of the last word in a string using a focused string-driven approach to handle spaces and trailing c…

Plus One

Given a number as an array of digits, increment it by one and return the updated array of digits.

Add Binary

Add Binary involves summing two binary strings and returning the result as a binary string using math and string manipul…

Sqrt(x)

Solve the Sqrt(x) problem using binary search to find the integer square root of a number without built-in operators.

Climbing Stairs

Climbing Stairs is a classic dynamic programming problem where you calculate distinct ways to reach the top using step t…

Remove Duplicates from Sorted List

Efficiently remove duplicates from a sorted linked list using precise pointer manipulation while maintaining node order …

Merge Sorted Array

Merge two sorted arrays into the first array in non-decreasing order, using a two-pointer approach.

Binary Tree Inorder Traversal

Binary Tree Inorder Traversal asks you to visit left subtree, node, then right subtree without losing position while mov…

Same Tree

Check whether two binary trees are identical by comparing structure and node values using DFS or BFS traversal strategie…

Symmetric Tree

Determine if a binary tree is symmetric by comparing left and right subtrees using DFS or BFS traversal techniques effic…

Maximum Depth of Binary Tree

Find the maximum depth of a binary tree using traversal techniques to track the longest path from root to leaf.

Convert Sorted Array to Binary Search Tree

Pick the middle element as root at each step so the sorted array becomes a height-balanced BST with valid ordering.

Balanced Binary Tree

Determine if a binary tree is height-balanced using tree traversal and state tracking techniques.

Minimum Depth of Binary Tree

Find the minimum depth of a binary tree, which is the shortest path from the root node to the nearest leaf node.