package tree;

import lombok.Data;
import lombok.ToString;

import java.util.List;

import static tree.InorderTraversal.inorderTraversal1;

/**
 * 删除二叉排序树的某个节点
 */
public class DeleteNode {

    public static void main(String[] args) {

        TreeNode root = new TreeNode(4);
        TreeNode TreeNode2 = new TreeNode(2);
        TreeNode TreeNode3 = new TreeNode(6);
        TreeNode TreeNode4 = new TreeNode(1);
        TreeNode TreeNode5 = new TreeNode(3);
        TreeNode TreeNode6 = new TreeNode(5);

        root.setLeft(TreeNode2);
        root.setRight(TreeNode3);
        TreeNode2.setLeft(TreeNode4);
        TreeNode2.setRight(TreeNode5);
        TreeNode3.setLeft(TreeNode6);

        deleteNode(root, 5);

        List<Integer> integers = inorderTraversal1(root);

        System.out.println(integers);


    }


    public static void deleteNode(TreeNode root, int value) {

        //删除的是有左右两个子树的节点
        TreeNode p = root;
        //记录当前节点的父节点
        TreeNode pp = null;

        //寻找到要删除的节点和他的父节点
        while (p != null && p.val != value) {
            pp = p;
            if (p.val < value) {
                p = p.right;
            } else if (p.val > value) {
                p = p.left;
            }
        }

        //判断是根据那个条件出来的
        if (p == null) {
            System.out.println("未找到要删除的节点的值...");
            return;
        } else if (p.val == value) {

            //p是要删除的节点,pp是他的父节点，如果pp=null,删除的就是root

            //判断删除的节点有几个子树
            if (p.left != null && p.right != null) {
                //左右子树都有,将找到右子树最小的节点，将他的值付给p，然后变成删除这个最小的数
                TreeNode min = p.right;
                //记录他的父节点
                TreeNode flag = p;
                while (min.left != null) {
                    flag = min;
                    min = min.left;
                }
                p.val = min.val;
                p = min;
                pp = flag;

            }

            //现在要删除的节点最多只有一个子树
            TreeNode child = null;
            if (p.left != null) {
                child = p.left;
            } else if (p.right != null) {
                child = p.right;
            }

            if (pp == null) {
                //要删除的是根节点
                root = child;
            } else if (pp.left == p) pp.left = child;
            else pp.right = child;

        }


    }


}