Java-二叉树-插入、删除、遍历

二叉树的具体特性和细节知识点，自行百度，直接上代码。

节点：节点内容、左子孩子、右子孩子、父亲

class Node {
    private int data;
    private Node leftChild;
    private Node rightChild;
    private Node parent;

    public Node getParent() {
        return parent;
    }

    public void setParent(Node parent) {
        this.parent = parent;
    }

    public Node(int data, Node leftChild, Node rightChild, Node parent) {
        this.data = data;
        this.leftChild = leftChild;
        this.rightChild = rightChild;
        this.parent = parent;

    }

    public int getData() {
        return data;
    }

    public void setData(int data) {
        this.data = data;
    }

    public Node getLeftChild() {
        return leftChild;
    }

    public void setLeftChild(Node leftChild) {
        this.leftChild = leftChild;
    }

    public Node getRightChild() {
        return rightChild;
    }

    public void setRightChild(Node rightChild) {
        this.rightChild = rightChild;
    }

}

二叉树构造和操作：

public class BinaryTree {
    private Node root;//根节点
    //插入节点
    public void insertNode(Node root, Node node) {

        Node current = root;
        while (true) {
            if (node.getData() < current.getData()) {
                if (current.getLeftChild() == null) {
                    node.setParent(current);
                    current.setLeftChild(node);
                    break;
                } else {
                    current = current.getLeftChild();
                }
            } else {
                if (current.getRightChild() == null) {
                    node.setParent(current);
                    current.setRightChild(node);
                    break;
                } else {
                    current = current.getRightChild();
                }

            }
        }
    }
    //删除节点
    public void deleteNode(Node node) {
        if (node.equals(root)) {
            root = null;
        } else if (node.getParent() != null) {
            if (node == node.getParent().getLeftChild()) {
                node.getParent().setLeftChild(null);
            } else {
                node.getParent().setRightChild(null);

            }
        }
    }

    //获取某节点的高度
    public int geHeight(Node node) {
        if (node == null) {
            return 0;
        } else {
            int leftHeight = geHeight(node.getLeftChild());
            int rightHeight = geHeight(node.getRightChild());
            int max = Math.max(leftHeight, rightHeight);
            return max + 1;
        }
    }

    //获取某节点的子节点个数
    public int getChildNodes(Node node) {
        if (node == null) {
            return 0;
        } else {
            int leftNodes = getChildNodes(node.getLeftChild());
            int rightNodes = getChildNodes(node.getRightChild());
            return leftNodes + rightNodes + 1;
        }
    }

    //先序遍历树
    public void PreOrder(Node root) {
        if (root == null)
            return;
        System.out.print(root.getData() + " ");
        PreOrder(root.getLeftChild());
        PreOrder(root.getRightChild());
    }

    //中序
    public void MidOrder(Node root) {
        if (root == null) return;
        MidOrder(root.getLeftChild());
        System.out.print(root.getData() + " ");
        MidOrder(root.getRightChild());
    }

    //后序
    public void LastOrder(Node root) {
        if (root == null) return;
        LastOrder(root.getLeftChild());
        LastOrder(root.getRightChild());
        System.out.print(root.getData() + " ");

    }

    public BinaryTree() {

    }

    public BinaryTree(Node root) {
        this.root = root;
    }

    public Node getRoot() {
        return root;
    }

    public void setRoot(Node root) {
        this.root = root;
    }

}

测试：

public class Main {
    public static void main(String[] args) {
        BinaryTree bt = new BinaryTree(new Node(1, null, null, null));
        int a[] = {5, 3, 2, 7, 4, 9, 8};
        for (int i = 0; i < 7; i++) {
            bt.insertNode(bt.getRoot(), new Node(a[i], null, null, null));
        }
//        System.out.println(bt.geHeight(root));//高度
//        bt.PreOrder(root);
//        System.out.println();
//        bt.MidOrder(root);
//        System.out.println();
//        bt.LastOrder(root);
//        System.out.println();
//        bt.deleteNode(bt.getRoot());
//        bt.PreOrder(bt.getRoot());
 //       System.out.println(bt.getChildNodes(bt.getRoot()));//子节点数

    }
}