---
title: "Linked Lists and Nodes That Point"
description: "A singly linked list stores a sequence in nodes containing values and next references. Insertion after an already-known node needs two next-reference assignments. Access by position requires following"
canonical: https://lightmysky.com/learn/computing/linked-lists-and-nodes-that-point-mt_HvY7_-M2Zj
source: https://lightmysky.com/learn/computing/linked-lists-and-nodes-that-point-mt_HvY7_-M2Zj.md
retrieved: 2026-11-12
---

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# Linked Lists and Nodes That Point

A singly linked list stores a sequence in nodes containing values and next references. Insertion after an already-known node needs two next-reference assignments. Access by position requires following links from the head.

Subject: Computing · Area: Algorithms & Data Structures · Ages 16 to 18
Page: https://lightmysky.com/learn/computing/linked-lists-and-nodes-that-point-mt_HvY7_-M2Zj

## Ready when they can

- Draw the pointer changes needed to insert and to delete a node in the middle
- Compare array access and ordered middle insertion with linked-list traversal and insertion after an already-known node
- Explain how null ends traversal and how another saved reference affects access to a detached tail

## Lesson: Chains made of pointing nodes

A singly linked list stores a sequence in nodes. Each node holds its own value and a next reference. Head refers to the first node; an empty list has null head. In a nonempty list, the last node's next is null. Head already identifies position one. Each next-reference step moves one position forward. Position numbers do not calculate node addresses as array indexes do.

*(drawing: Read the references in traversal order. These cells do not represent adjacent memory addresses.)*

**Example.** Begin with 10 -> 20 -> 30 -> 40. To insert new node X after 20, set X.next to node 30, then set node 20's next to X. This preserves the route to the old tail. For a separate deletion, return to the original chain. Set node 20's next to node 40 to bypass node 30. Unlinking a node and releasing its memory are separate tasks.

At an already-known predecessor, insertion takes two next assignments and deletion takes one. Finding that predecessor may require a walk first. Array access by index takes fixed work; linked-list access from head needs more steps for farther positions. Inserting into the middle of a contiguous array while preserving order shifts later values. Removing the first linked node changes head instead of a predecessor's next.

*(drawing: The assignments run in this order. The first preserves the old successor before its incoming link changes.)*

Before changing a link, keep a reference to any tail you still need. Setting a middle node's next to null stops traversal from head at that node. The tail is detached from that walk. A separate saved reference into the tail can still reach it. If no such entry reference remains, the program loses access to the detached nodes.

**Recap.** Relinking at a known node takes fixed work. Finding a position needs a walk. Preserve a route to the tail before changing its link.

*The lesson, questions and flashcards were written for this dataset.*

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Queues: First In, First Out](https://lightmysky.com/learn/computing/queues-first-in-first-out-mt_4U1bT0JW4g)

## Optional connections

- [Big-O Notation and Orders of Growth](https://lightmysky.com/learn/computing/big-o-notation-and-orders-of-growth-mt_mkqgxhJ509)

## Opens up

- [Trees and Binary Search Trees](https://lightmysky.com/learn/computing/trees-and-binary-search-trees-mt_7PGHiAY54b)
- [Hash Tables and Near-Constant Lookup](https://lightmysky.com/learn/computing/hash-tables-and-near-constant-lookup-mt_7v94MJEdmJ)