Trees are one of the most important data structures in computing. They appear in various forms and have a wide range of applications. In this post, we'll discuss the different types of trees in the data structure, their properties and how they're used in various contexts. We'll also provide some examples to see how trees are implemented in practice. So, if you're interested in learning more about these fascinating structures, read on!
What is a Tree in Data Structure?
A tree is a hierarchical data structure where each node has a maximum of two child nodes (sometimes referred to as successors). The topmost node in the tree is called the root node, and the bottommost nodes are called leaves. leaves. Between the root and leaves are node branches, a tree can be empty, with just a root node, or it can have many levels of nodes. The root node is unique, but other nodes can have multiple parent nodes.
For example, in a family tree, each person has only one biological mother and father, but they may have multiple grandparents, aunts, and uncles, etc. In computer science and software programming, trees are often used to represent the structure of HTML doc, trees are often used to represent the structure of HTML documents or file systems. They can also be used to store data such as DNA sequences or mathematical expressions. trees are often implemented using pointers in programming languages such as C++.
Types of Trees
After introducing trees in the data structure, we know they are used for different purposes. Here is an overview of some of the most popular types of trees in the data structure.
1. General Tree
A general tree is the most basic type of tree. It is made up of nodes that can have any number of child nodes. There is no specific relationship between the nodes; they can be traversed in any order. General trees are used when the relationship between the nodes is not important.
2. Binary tree
A binary tree is a special type of tree where each and every node can have no more than two child nodes. The left child node is always less than the parent node, and the right child node is always greater than or equal to the parent node. Binary trees are used when the nodes' relationship is important and needs to be kept in order.
3. Binary Search Tree
A binary search tree (BST) is a binary tree where every node has a value greater than all the values in its left subtree and less than all the values in its right subtree. BSTs are used when quickly searching for a value in a large dataset is important.
4. AVL Tree
An AVL tree (named after its inventors Adelson-Velsky and Landis) is a type of BST where each node has a value that is greater than all the values in its left subtree and less than all the values in its right subtree. In addition, an AVL tree must also be balanced, meaning that the difference between the heights of the left subtree and right subtree must be no more than 1. AVL trees are used when quickly searching for a value in a large dataset is important and when maintaining balance is also important.
5. Red-Black Tree
A red-black tree (RBT) is another type of self-balancing BST where each node has an extra bit associated with it that denotes its color (red or black). In addition, certain constraints must be met for an RBT to be valid: 1) every leaf (NULL) node is black, 2) if a node is red, then both its children must be black, 3) every simple path from any given node to any of its descendant leaves contains the same number of black nodes. RBTs are used when quickly searching for a value in a large dataset while also maintaining balance and ensuring constraint satisfaction is important.
6. N-ary Tree
An n-ary tree (or k-ary tree) generalizes BSTs and RBTs by allowing each node to have no more than k children instead of just 2 children as in BSTs/RBTs. N-ary trees are used when quick search timeshare is important and when the data does not fit well into a traditional binary tree structure(i.e., when k > 2).
Basic Terminologies Used in Tree Data Structure
Understanding basic tree data structure terminologies is crucial for anyone who wants to work with this type of data. Here, we will review some of the most important terms that you need to know.
- Root: The root is the topmost node in a tree. It does not have a parent and typically has zero or more child nodes.
- Child Node: A child node is any node that has a parent. Child nodes can have their own children (sub-nodes), which makes them parent nodes as well.
- Parent: A parent is a node that has at least one child node. Parent nodes can also have their own parents (super-nodes), making them child nodes.
Source
- Sibling: Siblings are nodes that share the same parent node. They can be thought of as "brothers and sisters" within the tree structure.
- Leaf Node: A leaf node is any node with no child nodes. Leaf nodes are typically the "end" of a tree branch.
- Internal Nodes: An internal node is a node that has at least one child node. Internal nodes are typically found "in-between" other nodes in a tree structure.
- Ancestor Node: An ancestor node is any node that is on the path from the root to the current node. Ancestor nodes can be thought of as "parents, grandparents, etc."
- Descendant: A descendant is a node that is a child, grandchild, great-grandchild, etc., of the current node. In other words, a descendant is any node that is "below" the current node in the tree structure.
- Height of a Node: The height of a node is the no. of edges from the node to the deepest leaf descendant. To put it another way, it is the "distance" from the node to the bottom of the tree.
- Depth of a Node: The depth of a node is the no. of edges from the root to the node. Therefore, it is the "distance" from the root to the node.
- Height of a Tree: The height of a tree is the height of its root node.
To get an insider's view into the advanced terminologies of trees in the data structure, you can look for Python Programming for beginners and experts in online courses. You can get the best out of your knowledge with the most reliable resources around.
Properties of Tree Data Structure
In computer science, a tree is a widely used data structure that simulates a hierarchical tree structure with a set of linked nodes. A tree data structure has the following properties:
- Recursive data structure
- Number of edges
- Depth of node x
- Height of node x
Read on to learn more about each of these properties of tree data structure in detail!
- Recursive Data Structure: A tree is a recursive data structure because it has a root node, and every node has zero or more child nodes. The root node is the topmost node in the tree, and the child nodes are located below the root node. If each node in the tree has zero or more child nodes, then the tree is said to be an n-aryl tree.
- Number of Edges: The number of edges in a tree is always one less than the number of nodes. This is because there is always one fewer edge than there are nodes in any given path from the root to any leaf node.
- Depth of Node x: The depth of a node is defined as the length of the shortest path from the root to that node. In other words, it is simply the number of edges on the path from the root to that particular node.
- Height of Node x: The height of a node is expressed as the length of the longest path from the node to any leaf node. In other words, it is simply the number of edges on the path from that particular node to the deepest leaf node.
By understanding these four properties, you will have a strong foundation on which to build more complex applications using trees!
Applications
In computer science, the tree data structure can be used to store hierarchical data. A tree traversal is a process of visiting each node in a tree. This can be done in different ways like pre-order, post-order, or in-order. Trees are also used to store data that naturally have hierarchical relationships, like the file system on our computers. Besides that, trees are also used in several applications like heaps, tries, and suffix trees. Let's take a look at some of these applications:
1) Storing Naturally Hierarchical Data
One of the main applications of tree data structure is to store hierarchical data. A lot of real-world data falls into this category. For instance, think about the file system on your computer. The files and folders are stored in a hierarchical fashion with a root folder (usually denoted by /). Each subfolder can further have more subfolders and so on. So when you want to store such data, a tree data structure is the most intuitive way to do it.
2) Organize Data
Trees can also be used as an organizational tool. For instance, a family tree is one such example where family relationships are represented using a tree-like structure. Similarly, trees can also be used to represent geographical features like states and cities in the USA or Countries and Continents in the world etc.
3) Trie
Trie is an efficient information retrieval data structure that is based on the key concept of words being prefixes of other words. It's also known as a radix or prefix tree. A Trie has three main properties – keys have consistent length, keys are in lexicographical order, and no key is a prefix of another key at the same level.
With these three conditions met, Trie provides an efficient way to retrieve strings from a dataset with a time complexity of O(M), where M is the length of the string retrieved. This makes it suitable for dictionary operations like autocomplete or spell check etc., which have become very popular these days with internet users all over the world.
4) Heap
A heap is a special type of binary tree where every parent node has either two child nodes or no child nodes, and every node satisfies one heap property – min heap or max heap property software programming. The Min heap property states that every parent node must have a value less than or equal to its child node, while the max heap property specifies that the parent node's value must be greater than or equal to the value of its child nodes (in the case of two children).
So depending upon which property we need to enforce upon our nodes, we call it min heap or max heap accordingly. Since heaps are complete binary trees, they provide a good performance guarantee for insertion and deletion operation with the time complexity of O(logN), where N number of elements currently present inside our heap data structure. Heaps also play an important role behind recommendation algorithms like the "People Also Watched" section on Netflix or Amazon Prime.
5) B-Tree and T-Tree
B-trees and T-trees are two types of trees in the data structure that are used to efficiently store large amounts of data. These trees are often used in databases because they allow for quick insertion and deletion of records while still maintaining fast access times.
6) Routing Table
A routing table maintains information about routes to particular network destinations, possibly via multiple network links/routers, thereby allowing efficient route discovery based on partial match instead of comparison against all known routes leading up to the destination, reducing routing overhead considerably, especially in high volume traffic networks.
Difference Between the Binary Tree and the Binary Search Tree
There are two main types of binary trees: the binary tree and the binary search tree. Both types of trees in data structure have their own unique characteristics and drawbacks.
The biggest difference between the two types of trees in the data structure is in how they are structured. A binary tree comprises two nodes, each of which can have zero, one, or two child nodes. On the other hand, a binary search tree is made up of nodes that each have two child nodes. This difference in structure means that binary trees are more efficient when searching for data, while binary search trees are more efficient when it comes to insertions and deletions.
Another difference between the two types of trees in the data structure is how they are traversed. Binary trees can be traversed in either a breadth-first or a depth-first manner, while binary search trees can only be traversed in a depth-first manner. This difference can be significant in performance; the breadth-first traversal of a binary tree is typically faster than the depth-first traversal of a binary search tree.
Overall, the choice of which tree to use depends on the application's specific needs. Both kinds of trees have their own advantages and disadvantages, so it is important to choose the type that best suits the application's needs.
Advantages of Tree Data Structure
1. Speed
Trees offer quicker search, insertion, and deletion than other data structures, such as linked lists, because of their shorter depth. For example, to delete an element from a linked list, you need to traverse the entire list until you find the element you want to delete, which could take O(n) time if the list is unsorted and up to O(log n) if it's sorted.
However, if you know the value of the element you want to delete beforehand, deleting it from a tree would only take O(log n) time since you can simply search for it and then remove it.
2. Flexibility
Trees do not have a fixed size like arrays, so they can grow and shrink as needed, making them very flexible, especially when dealing with dynamic data sets. For example, let's say you have an array of integers that can hold 100 elements, and you want to add the 101st element to it. Still, unfortunately, there's no more space left in the array, so you have to create a larger array big enough to hold all 101 elements and then copy all elements from the old array into a new one, which could be inefficient.
Furthermore, since treey does not have a fixed size, you could simply add the 101st element without worrying about creating larger arrays or copying data, making it more flexible than arrays.
3. Space Efficiency
Trees only require extra space for pointers since each node only needs to store the address or reference of its child nodes, unlike arrays which require extra space for every single element even if some of those elements are not used yet. For example, let's say we have an array of integers that can hold 1000 elements, but we only store 500 values. Then half of our array's memory would go wasted, which is not very space efficient.
In contrast, with trees, since each node only needs extra space for the address or reference of its child nodes, we don't waste any memory even if some parts of our tree are empty.
Conclusion
As we have seen, trees are a powerful data structure with many applications. Trees are used in computer science for various tasks, including storing information, representing hierarchical data, and providing efficient algorithms for operations such as insertion, deletion, and searching. There are different types of trees in data structure with varying properties that make them better suited for different tasks. However, all trees share some common features and characteristics. Understanding how to use trees can help you solve complex problems and improve your acquired high-level Java online course programming skills.