# Data Structures and Algorithms

A visual guide to the most important patterns and approaches for the coding interview.

This guide uses **interactive visualizations** to teach you the most important algorithm patterns for the coding interview.

Here's an example showing how a backtracking algorithm searches for the word HELLO:

#### Who is this for?

This is intended for those looking for a structured way to prepare for the coding interview using Python. It assumes you understand how and why to use fundamental data structures such as arrays, dictionaries, and sets.

#### How do I use this?

Unless they are labeled with a Pre-Requisite, the patterns can be completed in any order. If you’re short on time, start with Depth-First Search and Breadth-First Search, as they are the algorithms that most frequently show up during the coding interview.

Eliminating Pairs

Overview

Container With Most Water

3-Sum

Triangle Numbers

Pointers as Regions

Move Zeroes

Sort Colors

Trapping Rain Water

Variable-Length

Overview

Longest Substring Without Repeating Characters

Longest Repeating Character Replacement

Fixed-Length

Overview

Maximum Sum of Subarrays of Size K

Max Points You Can Obtain From Cards

Max Sum of Distinct Subarrays Length k

Overview

Can Attend Meetings

Insert Interval

Non-Overlapping Intervals

Merge Intervals

Employee Free Time

Overview

Valid Parentheses

Decode String

Longest Valid Parentheses

Monotonic Stack

Overview

Daily Temperatures

Largest Rectangle in Histogram

Overview

Linked List Cycle

Palindrome Linked List

Remove Nth Node From End of List

Reorder List

Swap Nodes in Pairs

Overview

Kth Largest Element in an Array

K Closest Points to Origin

Find K Closest Elements

Merge K Sorted Lists

Introduction

Binary Trees

Fundamentals

Return Values

Maximum Depth of a Binary Tree

Path Sum

Helper Functions and Global Variables

Validate Binary Search Tree

Calculate Tilt

Diameter of a Binary Tree

Path Sum II

Longest Univalue Path

Graphs

Overview

Adjacency List

Copy Graph

Graph Valid Tree

Matrices

Flood Fill

Types of DFS

Number of Islands

Surrounded Regions

Pacific Atlantic Water Flow

Introduction

Binary Trees

Overview

Level Order Sum

Rightmost Node

Zigzag Level Order

Maximum Width of Binary Tree

Graphs

Overview

Minimum Knight Moves

Rotting Oranges

01-Matrix

Bus Routes

Overview

Word Search

Solution Space Trees

Subsets

Generate Parentheses

Combination Sum