Introduction to binary sort tree
Binary sort tree is also called binary search tree. Simply speaking, the storage of data should conform to the principle: the nodes on the left should be smaller than the root node, and the nodes on the right should be larger than the root node, so as to avoid the same (the same can be placed left and right).
Learning binary sorting tree and realizing "add, delete, modify and query" can be completed with high efficiency.
Implementation ideas:
1. Create Node (define three variables, an adding method and a middle order traversal method (the results sorted before and after are not ordered))
2. Create a binary tree (define a root node, add adding method, add traversal method)
3. Create an instance, add an array recursively, and use the middle order traversal method output
Test code:
public class BinarySortTree { public static void main(String[] args) { // TODO Auto-generated method stub int arr [] = ; BinaryTree binaryTree = new BinaryTree(); //Add array recursively for(int i = 0; i < arr.length; i++) { binaryTree.add(new TreeNode(arr[i])); } //Ergodic output System.out.println("Middle order ergodic output~~"); binaryTree.postOrder(); } } //Create a binary tree class BinaryTree{ private TreeNode root; // public BinaryTree(Node root) { // this.root = root; // } //Add method public void add(TreeNode node) { if(root == null) { root = node; } else { this.root.add(node); } } //traversal method public void postOrder() { if(root != null) { this.root.postOrder(); } else { System.out.println("Binary tree is empty, unable to traverse sorting"); } } } //Create node class TreeNode{ private int value; private TreeNode left; private TreeNode right; public TreeNode(int value) { this.value = value; } @Override public String toString() { return "TreeNode [value=" + value + "]"; } //Add method public void add(TreeNode node) { //Determine the relationship between the incoming value and the value of the current node //If the value passed in is null, it will return directly if(node == null) { return; } //If the value passed in is less than the current value if(node.value < this.value) { //Judge whether the left child number of the current node is empty. If it is empty, the value less than the current node will be placed in the left node if(this.left == null) { this.left = node; //If the left sub node of the current node is not empty, the left sub tree will be judged by the cabinet lifting } else { this.left.add(node); } //If the value passed in is not less than the current value, it means it is greater than or equal to the current value, then it will be added to the right side of the current node } else { if(this.right == null) { this.right = node; } else { this.right.add(node); } } } //Postorder ergodic public void postOrder() { if(this.left != null) { this.left.postOrder(); } System.out.println(this); if(this.right != null) { this.right.postOrder(); } } }