Arrays and Linked Lists

Array Concepts

An array stores a fixed number of elements under one name. In most programming languages, all array elements must have the same data type.

Important terms:

In many languages, array indexes start at 0. For example, if an array has five fruits:

fruits = ["Apple", "Papaya", "Atis", "Santol", "Mango"]

Then:

fruits[0] = "Apple"
fruits[4] = "Mango"

Basic Array Operations

One-Dimensional and Two-Dimensional Arrays

A one-dimensional array is like a single row of values.

scores[0], scores[1], scores[2], ...

A two-dimensional array is arranged using rows and columns, like a table.

matrix[row][column]

Arrays: Strengths and Limitations

Arrays are easy to use because each item can be accessed directly by index. This makes reading an element fast.

However, insertion and deletion can be expensive when they happen in the middle of an array. Elements may need to shift left or right to keep the array organized.

For searching:

• an unsorted array may require checking each element one by one
• a sorted array can support faster searching, such as binary search

Linked List Concepts

A linked list stores data as nodes. Each node contains:

1. the data item
2. a link or reference to the next node

Unlike arrays, linked lists do not require all elements to be stored beside each other in memory. This allows them to grow or shrink while the program runs.

Linked List Strengths and Limitations

Common Linked List Variations

Diagram Descriptions

A simple linked list may be shown as circles or boxes connected by arrows. Each circle/box represents a node, and each arrow represents the link to the next node.

A dummy node is an extra node used to simplify operations near the beginning or end of a list. It may act as a placeholder so that insertion and deletion logic becomes more consistent.

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