C++ Full DSA RoadMap with helping code


🚀 1️⃣ LINKED LISTS A. Singly Linked List

Node structure

Insert (head, tail, middle)

Delete (head, tail, middle)

Search

Reverse a linked list

Middle of list

Detect loop

Remove loop

Merge two sorted lists

Intersection of two lists

B. Doubly Linked List

Insert (head, tail)

Delete (head, tail)

Forward/backward traversal

C. Circular Linked List

Insert & delete

Traversal

Applications (round-robin, scheduling)

D. Slow & Fast Pointer Techniques

Find middle

Detect cycle

Find cycle length

Find start of cycle

📦 2️⃣ STACKS Concepts

Push, Pop, Top

Overflow / Underflow

Applications

Important Problems

Reverse string using stack

Balanced parentheses

Next greater element

Stock span

Min stack

Postfix evaluation

Infix → Postfix conversion

🔄 3️⃣ QUEUES Concepts

Simple Queue

Circular Queue

Deque

Priority Queue

Double-ended queue

Important Problems

First non-repeating character

Sliding window maximum

Implement stack using queues

Implement queue using stacks

🔍 4️⃣ HASHING Concepts

Hash table

Hash functions

Chaining

Linear / Quadratic probing

Maps & unordered maps

Important Problems

Frequency counting

Two-sum

Longest subarray with sum k

Count distinct elements

Subarray with zero sum

Group anagrams

✨ 5️⃣ STRINGS Basic Concepts

String manipulation

Frequency array

Palindrome checking

Substring vs Subsequence

Advanced Techniques

Sliding window

Two pointers

Hashing for strings

KMP Algorithm

Z Algorithm

Rabin-Karp

Important Problems

Longest substring without repeating characters

Longest common prefix

String rotation

Pattern matching

🧭 6️⃣ ARRAYS (Advanced Techniques) Patterns

Two pointers

Kadane’s algorithm

Prefix sum

Sliding window

Difference array

Searching (binary search)

Problems

Largest subarray sum

Rotate array

Max product subarray

Majority element

Search in sorted rotated array

🔁 7️⃣ RECURSION & BACKTRACKING Core Concepts

Base case + recursion tree

Subset generation

Permutations

Backtracking template

Key Problems

N-Queens

Rat in a maze

Subset sum

Phone keypad combinations

Palindrome partitioning

⚡ 8️⃣ SORTING & SEARCHING Sorting

Merge sort

Quick sort

Heap sort

Counting sort

Bucket / Radix sort

Binary Search Problems

First & last occurrence

Peak element

Aggressive cows

Shipping capacity

Allocate pages

🧲 9️⃣ GREEDY ALGORITHMS Core Concepts

Greedy choice property

Activity selection

Fractional knapsack

Huffman coding

Minimum platforms

🌳 🔟 TREES Tree Basics

Terminology (node, edge, height, depth)

Tree traversals:

Inorder

Preorder

Postorder

Level-order

Binary Search Tree (BST)

Insert

Search

Delete

Predecessor & successor

Balanced vs unbalanced trees

Tree Problems

Height of tree

Diameter of tree

Check balanced tree

Lowest common ancestor (LCA)

Boundary traversal

Zig-zag traversal

Vertical order

🏗️ 1️⃣1️⃣ BINARY HEAP & PRIORITY QUEUE Concepts

Min heap

Max heap

Heapify

Heapsort

Problems

K largest elements

Merge K sorted lists

Kth smallest/largest element