DSA Patterns Sheet

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Curriculum Sheet

PROGRESS0/289 (0%)

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Status

Topics & Patterns

Array & String Patterns

0/52

Binary Search Patterns

0/12

Linked List Patterns

0/15

Stack & Queue Patterns

0/20

Interval Patterns

0/7

Heap Patterns

0/16

Tree Patterns

0/26

Graph Patterns

0/30

Trie Pattern

0/6

Backtracking Patterns

0/16

Greedy Pattern

0/10

Dynamic Programming Patterns

0/47

Bit Manipulation Pattern

0/8

String Matching Pattern

0/4

Advanced Data Structures

0/4

Math & Number Theory

0/8

Design Patterns

0/8

DSA CURRICULUM

DSA Patterns Mastery Sheet

Section A

Array & String Patterns

Pattern #1

Two Pointers

Use two pointers moving towards each other or in the same direction to solve problems in O(n) time on sorted/linear data.

0 / 12 (0%)

#125Valid Palindrome

Easy

#977Squares of a Sorted Array

Easy

#26Remove Duplicates from Sorted Array

Easy

#27Remove Element

Easy

#167Two Sum II – Input Array Is Sorted

Medium

#153Sum

Medium

#163Sum Closest

Medium

#184Sum

Medium

#75Sort Colors (Dutch National Flag)

Medium

#11Container With Most Water

Medium

#881Boats to Save People

Medium

#42Trapping Rain Water

Hard

Pattern #2

Sliding Window

Maintain a window of elements that expands/contracts to find optimal subarrays/substrings. Fixed-size or variable-size windows.

0 / 12 (0%)

#643Maximum Average Subarray I

Easy

#209Minimum Size Subarray Sum

Medium

#3Longest Substring Without Repeating Characters

Medium

#424Longest Repeating Character Replacement

Medium

#567Permutation in String

Medium

#438Find All Anagrams in a String

Medium

#904Fruit Into Baskets

Medium

#1004Max Consecutive Ones III

Medium

#1052Grumpy Bookstore Owner

Medium

#76Minimum Window Substring

Hard

#30Substring with Concatenation of All Words

Hard

#992Subarrays with K Different Integers

Hard

Pattern #3

Prefix Sum

Precompute cumulative sums so that any subarray sum can be computed in O(1). Often combined with hashing.

0 / 8 (0%)

#1480Running Sum of 1d Array

Easy

#724Find Pivot Index

Easy

#303Range Sum Query – Immutable

Easy

#238Product of Array Except Self

Medium

#525Contiguous Array

Medium

#974Subarray Sums Divisible by K

Medium

#1248Count Number of Nice Subarrays

Medium

#304Range Sum Query 2D – Immutable

Medium

Pattern #4

Hashing / HashMap

Use hash tables for O(1) average lookups. Map values to indices, frequencies, or complements.

0 / 10 (0%)

#1Two Sum

Easy

#217Contains Duplicate

Easy

#242Valid Anagram

Easy

#205Isomorphic Strings

Easy

#387First Unique Character in a String

Easy

#290Word Pattern

Easy

#49Group Anagrams

Medium

#560Subarray Sum Equals K

Medium

#128Longest Consecutive Sequence

Medium

#535Encode and Decode TinyURL

Medium

Pattern #5

Matrix Traversal / Spiral

Traverse 2D matrices in specific orders (spiral, diagonal, layer-by-layer) or modify in-place.

0 / 5 (0%)

#48Rotate Image

Medium

#54Spiral Matrix

Medium

#59Spiral Matrix II

Medium

#73Set Matrix Zeroes

Medium

#289Game of Life

Medium

Pattern #6

Cyclic Sort

When given numbers in range [1, n], place each number at its correct index. Finds missing/duplicate numbers in O(n) time, O(1) space.

0 / 5 (0%)

#268Missing Number

Easy

#448Find All Numbers Disappeared in an Array

Easy

#645Set Mismatch

Easy

#442Find All Duplicates in an Array

Medium

#41First Missing Positive

Hard

Section B

Binary Search Patterns

Pattern #7

Binary Search

Divide search space in half each iteration. Applies to sorted arrays, rotated arrays, and answer-space searching (binary search on answer).

0 / 12 (0%)

#704Binary Search

Easy

#35Search Insert Position

Easy

#34Find First and Last Position of Element in Sorted Array

Medium

#33Search in Rotated Sorted Array

Medium

#81Search in Rotated Sorted Array II

Medium

#153Find Minimum in Rotated Sorted Array

Medium

#162Find Peak Element

Medium

#74Search a 2D Matrix

Medium

#875Koko Eating Bananas

Medium

#1011Capacity To Ship Packages Within D Days

Medium

#410Split Array Largest Sum

Hard

#4Median of Two Sorted Arrays

Hard

Section C

Linked List Patterns

Pattern #8

Fast & Slow Pointers (Floyd's Cycle)

Use two pointers moving at different speeds to detect cycles, find midpoints, or detect patterns.

0 / 6 (0%)

#141Linked List Cycle

Easy

#876Middle of the Linked List

Easy

#202Happy Number

Easy

#142Linked List Cycle II

Medium

#234Palindrome Linked List

Easy

#287Find the Duplicate Number

Medium

Pattern #9

Linked List – In-Place Reversal & Manipulation

Reverse nodes in-place by manipulating pointers. Includes merge, reorder, rotation, and k-group operations.

0 / 9 (0%)

#206Reverse Linked List

Easy

#21Merge Two Sorted Lists

Easy

#19Remove Nth Node From End of List

Medium

#92Reverse Linked List II

Medium

#24Swap Nodes in Pairs

Medium

#61Rotate List

Medium

#143Reorder List

Medium

#138Copy List with Random Pointer

Medium

#25Reverse Nodes in k-Group

Hard

Section D

Stack & Queue Patterns

Pattern #10

Stack & Queue Fundamentals

LIFO/FIFO structures for parsing expressions, matching brackets, and simulating operations.

0 / 8 (0%)

#20Valid Parentheses

Easy

#232Implement Queue using Stacks

Easy

#225Implement Stack using Queues

Easy

#155Min Stack

Medium

#150Evaluate Reverse Polish Notation

Medium

#394Decode String

Medium

#227Basic Calculator II

Medium

#224Basic Calculator

Hard

Pattern #11

Monotonic Stack

Maintain a stack where elements are in increasing or decreasing order. Finds next greater/smaller elements efficiently.

0 / 8 (0%)

#496Next Greater Element I

Easy

#503Next Greater Element II

Medium

#739Daily Temperatures

Medium

#901Online Stock Span

Medium

#735Asteroid Collision

Medium

#907Sum of Subarray Minimums

Medium

#84Largest Rectangle in Histogram

Hard

#85Maximal Rectangle

Hard

Pattern #12

Monotonic Queue / Deque

0 / 4 (0%)

#239Sliding Window Maximum

Hard

#862Shortest Subarray with Sum at Least K

Hard

#1425Constrained Subsequence Sum

Hard

#1696Jump Game VI

Medium

Section E

Interval Patterns

Pattern #13

Merge Intervals

Sort intervals by start time and merge/process overlapping intervals. Core pattern for scheduling problems.

0 / 7 (0%)

#252Meeting Rooms

Easy

#56Merge Intervals

Medium

#57Insert Interval

Medium

#435Non-overlapping Intervals

Medium

#986Interval List Intersections

Medium

#452Minimum Number of Arrows to Burst Balloons

Medium

#253Meeting Rooms II

Medium

Section F

Heap Patterns

Pattern #14

Heap / Top K Elements

Use min-heap or max-heap to efficiently maintain the K largest/smallest/most-frequent elements.

0 / 8 (0%)

#1046Last Stone Weight

Easy

#215Kth Largest Element in an Array

Medium

#347Top K Frequent Elements

Medium

#973K Closest Points to Origin

Medium

#451Sort Characters By Frequency

Medium

#692Top K Frequent Words

Medium

#621Task Scheduler

Medium

#767Reorganize String

Medium

Pattern #15

Two Heaps / Median Pattern

0 / 3 (0%)

#295Find Median from Data Stream

Hard

#480Sliding Window Median

Hard

#502IPO

Hard

Pattern #16

K-way Merge

0 / 5 (0%)

#264Ugly Number II

Medium

#378Kth Smallest Element in a Sorted Matrix

Medium

#373Find K Pairs with Smallest Sums

Medium

#23Merge k Sorted Lists

Hard

#632Smallest Range Covering Elements from K Lists

Hard

Section G

Tree Patterns

Pattern #17

Tree – BFS / Level Order Traversal

Use a queue to process tree nodes level by level. Useful for level-based operations.

0 / 8 (0%)

#637Average of Levels in Binary Tree

Easy

#111Minimum Depth of Binary Tree

Easy

#993Cousins in Binary Tree

Easy

#102Binary Tree Level Order Traversal

Medium

#103Binary Tree Zigzag Level Order Traversal

Medium

#199Binary Tree Right Side View

Medium

#116Populating Next Right Pointers in Each Node

Medium

#117Populating Next Right Pointers in Each Node II

Medium

Pattern #18

Tree – DFS (Preorder/Inorder/Postorder)

Recursive or iterative depth-first traversal. Solve problems using top-down or bottom-up recursion.

0 / 11 (0%)

#104Maximum Depth of Binary Tree

Easy

#226Invert Binary Tree

Easy

#101Symmetric Tree

Easy

#112Path Sum

Easy

#543Diameter of Binary Tree

Easy

#437Path Sum III

Medium

#236Lowest Common Ancestor of a Binary Tree

Medium

#105Construct Binary Tree from Preorder and Inorder Traversal

Medium

#114Flatten Binary Tree to Linked List

Medium

#124Binary Tree Maximum Path Sum

Hard

#297Serialize and Deserialize Binary Tree

Hard

Pattern #19

BST (Binary Search Tree) Properties

0 / 7 (0%)

#108Convert Sorted Array to Binary Search Tree

Easy

#235Lowest Common Ancestor of a Binary Search Tree

Medium

#98Validate Binary Search Tree

Medium

#230Kth Smallest Element in a BST

Medium

#701Insert into a Binary Search Tree

Medium

#450Delete Node in a BST

Medium

#669Trim a Binary Search Tree

Medium

Section H

Graph Patterns

Pattern #20

Graph – BFS / DFS Traversal

Explore graphs using BFS (shortest path in unweighted) or DFS (connectivity, components). Includes grid-based graph problems.

0 / 12 (0%)

#733Flood Fill

Easy

#200Number of Islands

Medium

#547Number of Provinces

Medium

#130Surrounded Regions

Medium

#133Clone Graph

Medium

#54201 Matrix

Medium

#994Rotting Oranges

Medium

#417Pacific Atlantic Water Flow

Medium

#752Open the Lock

Medium

#1162As Far from Land as Possible

Medium

#127Word Ladder

Hard

#934Shortest Bridge

Medium

Pattern #21

Graph – Shortest Path (Dijkstra / Bellman-Ford)

0 / 6 (0%)

#743Network Delay Time

Medium

#787Cheapest Flights Within K Stops

Medium

#1514Path with Maximum Probability

Medium

#1631Path with Minimum Effort

Medium

#1334Find the City With the Smallest Number of Neighbors at a Threshold Distance

Medium

#778Swim in Rising Water

Hard

Pattern #22

Topological Sort

0 / 6 (0%)

#207Course Schedule

Medium

#210Course Schedule II

Medium

#310Minimum Height Trees

Medium

#2115Find All Possible Recipes from Given Supplies

Medium

#1203Sort Items by Groups Respecting Dependencies

Hard

#329Longest Increasing Path in a Matrix

Hard

Pattern #23

Union Find / Disjoint Set Union

0 / 6 (0%)

#990Satisfiability of Equality Equations

Medium

#684Redundant Connection

Medium

#721Accounts Merge

Medium

#1319Number of Operations to Make Network Connected

Medium

#947Most Stones Removed with Same Row or Column

Medium

#959Regions Cut By Slashes

Medium

Section I

Trie Pattern

Pattern #24

Trie (Prefix Tree)

0 / 6 (0%)

#208Implement Trie (Prefix Tree)

Medium

#211Design Add and Search Words Data Structure

Medium

#648Replace Words

Medium

#720Longest Word in Dictionary

Medium

#1268Search Suggestions System

Medium

#212Word Search II

Hard

Section J

Backtracking Patterns

Pattern #25

Backtracking – Subsets / Combinations / Permutations

Systematically explore all possible configurations by building candidates incrementally and abandoning (backtracking) when constraints are violated.

0 / 8 (0%)

#77Combinations

Medium

#78Subsets

Medium

#90Subsets II

Medium

#46Permutations

Medium

#47Permutations II

Medium

#39Combination Sum

Medium

#40Combination Sum II

Medium

#216Combination Sum III

Medium

Pattern #26

Backtracking – General / Constraint Satisfaction

0 / 8 (0%)

#17Letter Combinations of a Phone Number

Medium

#22Generate Parentheses

Medium

#79Word Search

Medium

#93Restore IP Addresses

Medium

#131Palindrome Partitioning

Medium

#51N-Queens

Hard

#37Sudoku Solver

Hard

#282Expression Add Operators

Hard

Section K

Greedy Pattern

Pattern #27

Greedy Algorithms

0 / 10 (0%)

#455Assign Cookies

Easy

#121Best Time to Buy and Sell Stock

Easy

#860Lemonade Change

Easy

#53Maximum Subarray (Kadane's Algorithm)

Medium

#55Jump Game

Medium

#45Jump Game II

Medium

#134Gas Station

Medium

#763Partition Labels

Medium

#406Queue Reconstruction by Height

Medium

#135Candy

Hard

Section L

Dynamic Programming Patterns

Pattern #28

DP – Fibonacci / Linear 1D DP

Each state depends on a fixed number of previous states. The simplest DP pattern.

0 / 6 (0%)

#509Fibonacci Number

Easy

#1137N-th Tribonacci Number

Easy

#70Climbing Stairs

Easy

#198House Robber

Medium

#213House Robber II

Medium

#91Decode Ways

Medium

Pattern #29

DP – 0/1 Knapsack

0 / 4 (0%)

#416Partition Equal Subset Sum

Medium

#494Target Sum

Medium

#1049Last Stone Weight II

Medium

#474Ones and Zeroes

Medium

Pattern #30

DP – Unbounded Knapsack

0 / 5 (0%)

#322Coin Change

Medium

#518Coin Change II

Medium

#279Perfect Squares

Medium

#139Word Break

Medium

#983Minimum Cost For Tickets

Medium

Pattern #31

DP – LCS / LIS (Subsequence Patterns)

Find longest common/increasing subsequences. Core pattern: compare characters and build 2D DP table.

0 / 8 (0%)

#300Longest Increasing Subsequence

Medium

#1143Longest Common Subsequence

Medium

#583Delete Operation for Two Strings

Medium

#718Maximum Length of Repeated Subarray

Medium

#673Number of Longest Increasing Subsequence

Medium

#72Edit Distance

Medium

#1092Shortest Common Supersequence

Hard

#354Russian Doll Envelopes

Hard

Pattern #32

DP – Palindromic Subsequence / Substring

0 / 4 (0%)

#5Longest Palindromic Substring

Medium

#647Palindromic Substrings

Medium

#516Longest Palindromic Subsequence

Medium

#1312Minimum Insertion Steps to Make a String Palindrome

Hard

Pattern #33

DP – Matrix / Grid Path

0 / 6 (0%)

#62Unique Paths

Medium

#63Unique Paths II

Medium

#64Minimum Path Sum

Medium

#120Triangle

Medium

#221Maximal Square

Medium

#174Dungeon Game

Hard

Pattern #34

DP – Interval / Matrix Chain Multiplication

0 / 5 (0%)

#486Predict the Winner

Medium

#877Stone Game

Medium

#1130Minimum Cost Tree From Leaf Values

Medium

#312Burst Balloons

Hard

#664Strange Printer

Hard

Pattern #35

DP – State Machine / Stock Problems

0 / 5 (0%)

#122Best Time to Buy and Sell Stock II

Medium

#714Best Time to Buy and Sell Stock with Transaction Fee

Medium

#309Best Time to Buy and Sell Stock with Cooldown

Medium

#123Best Time to Buy and Sell Stock III

Hard

#188Best Time to Buy and Sell Stock IV

Hard

Pattern #36

DP – On Strings

0 / 4 (0%)

#97Interleaving String

Medium

#115Distinct Subsequences

Hard

#10Regular Expression Matching

Hard

#44Wildcard Matching

Hard

Section M

Bit Manipulation Pattern

Pattern #37

Bit Manipulation

Use bitwise operations (AND, OR, XOR, shifts) for O(1) space tricks and O(n) solutions.

0 / 8 (0%)

#191Number of 1 Bits

Easy

#190Reverse Bits

Easy

#231Power of Two

Easy

#136Single Number

Easy

#338Counting Bits

Easy

#201Bitwise AND of Numbers Range

Medium

#137Single Number II

Medium

#260Single Number III

Medium

Section N

String Matching Pattern

Pattern #38

String Matching / KMP / Z-Algorithm

0 / 4 (0%)

#28Find the Index of the First Occurrence in a String

Easy

#459Repeated Substring Pattern

Easy

#214Shortest Palindrome

Hard

#1392Longest Happy Prefix

Hard

Section O

Advanced Data Structures

Pattern #39

Segment Tree / Binary Indexed Tree

0 / 4 (0%)

#307Range Sum Query – Mutable

Medium

#315Count of Smaller Numbers After Self

Hard

#493Reverse Pairs

Hard

#327Count of Range Sum

Hard

Section P

Math & Number Theory

Pattern #40

Math & Number Theory

0 / 8 (0%)

#9Palindrome Number

Easy

#13Roman to Integer

Easy

#168Excel Sheet Column Title

Easy

#172Factorial Trailing Zeroes

Medium

#7Reverse Integer

Medium

#50Pow(x, n)

Medium

#204Count Primes (Sieve of Eratosthenes)

Medium

#43Multiply Strings

Medium

Section Q

Design Patterns

Pattern #41

System / Data Structure Design

0 / 8 (0%)

#706Design HashMap

Easy

#707Design Linked List

Medium

#622Design Circular Queue

Medium

#355Design Twitter

Medium

#380Insert Delete GetRandom O(1)

Medium

#341Flatten Nested List Iterator

Medium

#146LRU Cache

Medium

#460LFU Cache

Hard