Reversing a Link List using Recursion

Duration: 4 min

This video lesson is available to enrolled students.

Return to /learn/COCUBES-PREPARATION/data-structures/linked-list/structure-modification-pointer-logic/asset-reversing-a-link-list-using-recursion after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. Quantitative Aptitude: Number System, Divisibility Rules, HCF LCM, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Mixture and Alligation, Partnership, Age Problems, Time and Work, Pipe and Cistern, Speed Time and Distance, Algebra, Arithmetic, Data Interpretation, Sequence and Series (Series), Logarithm, Powers and Exponents (Surds and Indices), Permutation and Combination, Probability, Speed Mathematics and Basic Mathematics, Trigonometry
  2. Logical Reasoning: Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Seating Arrangements, Puzzle Solving (Puzzles), Data Arrangement, Syllogisms, Inequality, Data Sufficiency, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Venn Diagram, Logical Sequence Of Words, Calendar, Clock, Cubes & Dices, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning)
  3. Verbal Ability: Noun, Pronoun, Adjectives, Verb, Adverb, Tenses, Subject Verb Agreement (Verb Noun Agreement), Articles, Preposition, Conjunction, Modals, Determiner, Vocabulary, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Active Passive Voice (Voice), Direct and Indirect Speech, Sentence Construction
  4. Data Structures (Domain Test): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  5. Algorithms (Domain Test): Algorithm Analysis, Sorting Algorithms, Time Complexity Analysis, Greedy Algorithms
  6. OOPs (Domain Test): Object Oriented Programming (OOPS)
  7. DBMS (Domain Test): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  8. SQL (Domain Test): SQL
  9. Operating Systems (Domain Test): Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  10. Computer Networks (Domain Test): Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
  11. Coding: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir
  12. Written English Test: English Writing Ability
  13. Psychometric Test: Behavioral Assessment (Behavioral Competency Profiling) (Psychometric Test)
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a detailed walkthrough of reversing a singly linked list using a recursive algorithm in C. The instructor begins by presenting the code structure, specifically the `main` function calling `reverse(null, head)` and the recursive `reverse` function definition. He explains the two-pointer approach where `previous` and `current` are passed down the recursion stack. The core of the lesson involves a step-by-step trace of the execution on a list containing nodes 'a', 'b', 'c', and 'd', demonstrating how the call stack builds up and then unwinds to update the pointers in reverse order.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the problem of reversing a linked list and displays the C code on the screen. He highlights the `main` function calling `reverse(null, head)` and the function signature `Void reverse(struct node* previous, current)`. He explains the logic: if `current` is not null, it recursively calls itself with `current` as the new `previous` and `current->next` as the new `current`. The base case is when `current` is null, at which point `Head` is set to `previous`. The instructor begins tracing the execution, writing down the call stack: `reverse(null, 10)`, `reverse(10, 20)`, `reverse(20, 30)`, and `reverse(30, 40)`, representing the addresses of nodes 'a', 'b', 'c', and 'd' respectively.

  2. 2:00 – 3:55 02:00-03:55

    The lecture continues with the base case execution and the unwinding phase. The instructor shows the final recursive call `reverse(40, null)`, where the condition `current != null` fails, triggering the `Else` block to set `Head = 40`. As the recursion returns, the line `Current->link = previous` executes. He traces this specifically: node 'd' (40) points to 'c' (30), node 'c' (30) points to 'b' (20), node 'b' (20) points to 'a' (10), and finally node 'a' (10) points to null. He draws the final state of the linked list on the diagram, showing the arrows reversed from d -> c -> b -> a, confirming the list is now reversed with 'd' as the new head.

The video successfully demystifies recursive linked list reversal by combining code analysis with a visual trace. The instructor effectively uses the call stack diagram to show how the 'previous' pointer accumulates the reversed sequence as the recursion unwinds. By explicitly mapping node addresses (10, 20, 30, 40) to the function arguments, he clarifies how the `Current->link = previous` statement physically reverses the pointers in memory, ensuring students understand both the logical flow and the memory manipulation involved.

Loading lesson…