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Patterns for Coding Questions

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Introduction

Who should take this course?Course Overview

Pattern: Sliding Window

Introduction Maximum Sum Subarray of Size K (easy)Smallest Subarray with a given sum (easy)Longest Substring with K Distinct Characters (medium)Fruits into Baskets (medium)No-repeat Substring (hard)Longest Substring with Same Letters after Replacement (hard)Longest Subarray with Ones after Replacement (hard)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3 Problem Challenge 4 Solution Review: Problem Challenge 4

Pattern: Two Pointers

Introduction Pair with Target Sum (easy)Remove Duplicates (easy)Squaring a Sorted Array (easy)Triplet Sum to Zero (medium)Triplet Sum Close to Target (medium)Triplets with Smaller Sum (medium)Subarrays with Product Less than a Target (medium)Dutch National Flag Problem (medium)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3

Pattern: Fast and Slow Patterns

Introduction LinkedList Cycle (easy)Start of LinkedList Cycle (medium)Happy Number (medium)Middle of the LinkedList (easy)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3

Pattern: Merge Intervals

Introduction Merge Intervals (medium)Insert Interval (medium)Intervals Intersection (medium)Conflicting Appointments (medium)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3

Pattern: Cyclic Sort

Introduction Cyclic Sort (easy)Find the Missing Number (easy)Find all Missing Numbers (easy)Find the Duplicate Number (easy)Find all Duplicate Numbers (easy)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3

Pattern: In-place Reversal of a LinkedList

Introduction Reverse a LinkedList (easy)Reverse a Sub-list (medium)Reverse every K-element Sub-list (medium)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2

Pattern: Tree Breadth First Search

Introduction Binary Tree Level Order Traversal (easy)Reverse Level Order Traversal (easy)Zigzag Traversal (medium)Level Averages in a Binary Tree (easy)Minimum Depth of a Binary Tree (easy)Level Order Successor (easy)Connect Level Order Siblings (medium)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2

Pattern: Tree Depth First Search

Binary Tree Path Sum (easy)

All Paths for a Sum (medium)

Sum of Path Numbers (medium)

Path With Given Sequence (medium)

Count Paths for a Sum (medium)

Problem Challenge 1

Solution Review: Problem Challenge 1

Problem Challenge 2

Solution Review: Problem Challenge 2

Pattern: Two Heaps

Introduction Find the Median of a Number Stream (medium)Sliding Window Median (hard)Maximize Capital (hard)Problem Challenge 1 Solution Review: Problem Challenge 1

Pattern: Subsets

Introduction Subsets (easy)Subsets With Duplicates (easy)Permutations (medium)String Permutations by changing case (medium)Balanced Parentheses (hard)Unique Generalized Abbreviations (hard)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3

Pattern: Modified Binary Search

Introduction Order-agnostic Binary Search (easy)Ceiling of a Number (medium)Next Letter (medium)Number Range (medium)Search in a Sorted Infinite Array (medium)Minimum Difference Element (medium)Bitonic Array Maximum (easy)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3

Pattern: Bitwise XOR

Introduction Single Number (easy)Two Single Numbers (medium)Complement of Base 10 Number (medium)Problem Challenge 1 Solution Review: Problem Challenge 1

Pattern: Top 'K' Elements

Introduction Top 'K' Numbers (easy)Kth Smallest Number (easy)'K' Closest Points to the Origin (easy)Connect Ropes (easy)Top 'K' Frequent Numbers (medium)Frequency Sort (medium)Kth Largest Number in a Stream (medium)'K' Closest Numbers (medium)Maximum Distinct Elements (medium)Sum of Elements (medium)Rearrange String (hard)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2 Problem Challenge 3 Solution Review: Problem Challenge 3

Pattern: K-way merge

Introduction Merge K Sorted Lists (medium)Kth Smallest Number in M Sorted Lists (Medium)Kth Smallest Number in a Sorted Matrix (Hard)Smallest Number Range (Hard)Problem Challenge 1 Solution Review: Problem Challenge 1

Pattern : 0/1 Knapsack (Dynamic Programming)

Introduction 0/1 Knapsack (medium)Equal Subset Sum Partition (medium)Subset Sum (medium)Minimum Subset Sum Difference (hard)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2

Pattern: Topological Sort (Graph)

Introduction Topological Sort (medium)Tasks Scheduling (medium)Tasks Scheduling Order (medium)All Tasks Scheduling Orders (hard)Alien Dictionary (hard)Problem Challenge 1 Solution Review: Problem Challenge 1 Problem Challenge 2 Solution Review: Problem Challenge 2

Miscellaneous

Kth Smallest Number (hard)

Conclusions

Where to Go from Here

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Solution Review: Problem Challenge 1

Solution Review: Problem Challenge 1

Tree Diameter (medium) #

Given a binary tree, find the length of its diameter. The diameter of a tree is the number of nodes on the longest path between any two leaf nodes. The diameter of a tree may or may not pass through the root.

Note: You can always assume that there are at least two leaf nodes in the given tree.

Solution #

This problem follows the ...