Data structure facts for kids

A data structure is a special way to organize and store information in a computer. Think of it like organizing your toys or books so you can find them easily later. When data is organized well, computers can work with it much faster and more efficiently.

Data structures are like the blueprints for how data is arranged. They are different from "abstract data types," which are more like the idea or concept of how data should behave. For example, a "list" is an abstract idea of a sequence of items. A "linked list" is a specific data structure that shows how to actually build that list in a computer's memory, often by connecting each item to the next one with a "pointer" or "reference." Choosing the right data structure is a very important part of programming!

Common Ways to Organize Data

Arrays: Simple Lists

The simplest way to store a collection of items is using an array. Imagine a row of numbered boxes, and each box can hold one piece of information, like a number or a word. All the items in an array are usually of the same type.

Arrays are great because you can quickly find any item if you know its box number (called an index). For example, if you want the item in box number 5, the computer can go straight to it.

A common thing about arrays is that they often have a fixed size. This means once you decide how many boxes it has, it's hard to add more without creating a whole new, bigger row of boxes and moving everything over. Arrays are used in almost every computer program and are super important for building other data structures.

Linked Lists: Flexible Chains

A linked list is another way to store information, but it's more like a chain. Each piece of information (called a node) is linked to the next one. Think of it like a scavenger hunt where each clue tells you where to find the next clue. These links are called pointers.

Each node points to another node.

Unlike arrays, linked lists are very flexible. You can easily add or remove items anywhere in the chain without having to move everything else around. However, finding a specific item might take a bit longer because the computer has to follow the links one by one until it reaches the right node.

Stacks: Last In, First Out

A stack is a data structure where you can only add or remove items from the very top. Imagine a stack of plates: you always put a new plate on top, and you always take the top plate off first. This is why stacks are called "Last In, First Out" (LIFO). The last item you put in is the first one you take out.

There are three main things you can do with a stack:

• Pushing: Adding a new item to the top of the stack.
• Popping: Removing the top item from the stack.
• Peeking: Looking at the top item without removing it.

Stacks are used a lot in programming, for example, to keep track of actions that need to be undone (like the "undo" button in a word processor).

Queues: First In, First Out

A queue is like a line of people waiting for something. The first person to join the line is the first person to leave. This is why queues are called "First In, First Out" (FIFO).

• Enqueuing: Adding an item to the back of the queue.
• Dequeuing: Removing an item from the front of the queue.

Queues are used in many places, like managing tasks for a printer (the first document sent to print is the first one printed) or handling messages in a computer system.

Graphs: Connected Networks

A graph is a way to represent connections between different things. Imagine a map where cities are points and roads are lines connecting them. In a graph, the "cities" are called nodes or vertices, and the "roads" are called edges or arcs.

Graphs are super useful for showing relationships, like how friends are connected on social media, how web pages link to each other, or even planning the shortest route between two places.

Trees: Hierarchical Structures

A tree is a special type of graph that looks like an upside-down tree, with a single starting point called the "root" at the top, and branches spreading downwards. Each node in a tree can have "children" nodes, but each child only has one "parent" node.

Trees are excellent for organizing data in a hierarchy, like a family tree, the file system on your computer (folders inside folders), or an index in a book. They help computers find information very quickly, especially in a "binary tree" where each node has at most two branches.

Hash Tables: Super-Fast Lookups

A hash table is a clever way to store data so you can find it almost instantly. It works by using a special calculation (called a hash function) to figure out exactly where to put each piece of data in an array. This calculation gives a unique "hash value" for each item.

Because the computer knows exactly where to look based on the hash value, retrieving data from a hash table is incredibly fast, no matter how much data there is!

Images for kids

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  The standard type hierarchy of the programming language Python 3.

See also

In Spanish: Estructura de datos para niños