二叉树bst删除 删除叶子节点代码

package tree.bst;

public class bstDemo {
    public static void main(String[] args) {
        System.out.println("二叉排序树");

        BstTree bstTree = new BstTree();

        int[] arr = {7,3,10,12,5,1,9,2};
        for (int i = 0; i < arr.length; i++) {
            bstTree.addNode(new Node(arr[i]));
        }

        bstTree.infixOrder();

        // 删除叶子节点
        bstTree.deleteNode(12);
        System.out.println("删除后");
        bstTree.infixOrder();

    }
}

class BstTree
{
    private Node root;

    public void  addNode(Node node)
    {
        if(root == null){
            root = node;
        } else {
            root.add(node);
        }
    }

    public void infixOrder()
    {
        if(root == null){
            return ;
        }

        root.infixOrder();
    }

    public Node search(int value){
        if(root == null){
            return null;
        } else {
            return root.search(value);
        }
    }

    public Node searchParent(int value){
        if(root == null){
            return null;
        } else {
            return root.searchParent(value);
        }
    }

    public void deleteNode(int value){
        if(root == null){
            return;
        }

        // find thi node
        Node targetNode = this.search(value);
        // 如果没有找到要删除的节点
        if(targetNode == null) {
            return;
        }

        // 没有父节点
        if(root.left == null && root.right == null){
            root = null;
            return ;
        }

        Node parent = searchParent(value);

        //叶子节点
        if(targetNode.left == null && targetNode.right == null) {
            if(parent.left != null && parent.left.value == value){
                parent.left = null;
            } else if(parent.right != null && parent.right.value == value){
                parent.right = null;
            }
        }
    }
}

class Node {
    public int value;
    public Node left;
    public Node right;

    public Node(int value) {
        this.value = value;
    }

    // find node
    public Node search(int value){
        if(value == this.value){
            return this;
        } else if(value < this.value){
            // left tree find
            if(this.left == null){
                return null;
            }
            return this.left.search(value);
        } else {
            if(this.right == null){
                return null;
            }

            return this.right.search(value);
        }

    }

    // 查找要删除的节点的父节点
    public Node searchParent(int value)
    {
        if(this.left != null && this.left.value == value
                ||(this.right!=null && this.right.value==value)){
            return this;
        } else{
            if(value < this.value && this.left !=null){
                return this.left.searchParent(value);
            } else if(value >=this.value && this.right != null) {
                return this.right.searchParent(value);
            } else {
                return null;
            }
        }
    }

    // 添加节点
    public void add(Node node){
        if(node == null) {
            return ;
        }

        // 添加 left
        if(node.value < this.value){
            if(this.left == null){
                this.left = node;
            } else {
                this.left.add(node);
            }
        }

        // 添加到right
        if(node.value > this.value){
            if(this.right == null){
                this.right = node;
            } else {
                this.right.add(node);
            }
        }

    }

    // 中序便利
    public void infixOrder()
    {
        if(this.left != null){
            this.left.infixOrder();
        }

        System.out.println(this);

        if(this.right != null){
            this.right.infixOrder();
        }
    }

    @Override
    public String toString() {
        return "Node{" +
                "value=" + value +
                '}';
    }
}