《程序员代码面试指南》第三章 二叉树问题 调整搜索二叉树中两个错误的节点

题目

调整搜索二叉树中两个错误的节点

java代码

package com.lizhouwei.chapter3;

import java.util.Stack;

/**
 * @Description:调整搜索二叉树中两个错误的节点
 * @Author: lizhouwei
 * @CreateDate: 2018/4/17 19:43
 * @Modify by:
 * @ModifyDate:
 */
public class Chapter3_10 {

    public Node[] getTwoErrNode(Node head) {
        Node pre = null;
        Node[] errNode = new Node[2];
        Stack<Node> stack = new Stack<>();
        while (!stack.isEmpty() || head != null) {
            if (head != null) {
                stack.push(head);
                head = head.left;
            } else {
                head = stack.pop();
                if (pre != null && pre.value > head.value) {
                    errNode[0] = errNode[0] == null ? pre : errNode[0];
                    errNode[1] = head;
                }
                pre = head;
                head = head.right;
            }
        }
        return errNode;
    }

    public Node[] getTwoErrParents(Node head, Node head1, Node head2) {
        Node pre = null;
        Node[] errParents = new Node[2];
        Stack<Node> stack = new Stack<>();
        stack.push(head);
        while (!stack.isEmpty()) {
            head = stack.pop();
            if (head.left == head1 || head.right == head1) {
                errParents[0] = head;
            }
            if (head.left == head2 || head.right == head2) {
                errParents[1] = head;
            }

            if (head.right != null) {
                stack.push(head.right);
            }
            if (head.left != null) {
                stack.push(head.left);
            }
        }
        return errParents;
    }

    //分14中情况
    public Node adjustTree(Node head) {
        Node[] errNode = getTwoErrNode(head);
        Node e1 = errNode[0];
        Node e1L = e1.left;
        Node e1R = e1.right;
        Node e2 = errNode[1];
        Node e2L = e2.left;
        Node e2R = e2.right;
        Node[] parents = getTwoErrParents(head, e1, e2);
        Node e1P = parents[0];
        Node e2P = parents[1];
        e1.left = e2L;
        e1.right = e2R;
        e2.left = e1L;
        e2.right = e1R;
        if (e1 == head) {
            if (e1.right == e2) {
                e2.right = e1;
            } else if (e2P.left == e2) {
                e2P.left = e1;
            } else if (e2P.right == e2) {
                e2P.right = e1;
            }
            return e2;
        } else if (e2 == head) {
            if (e2.left == e1) {
                e1.left = e2;
            } else if (e1P.left == e1) {
                e1P.left = e2;
            } else if (e1P.right == e1) {
                e1P.right = e2;
            }
            return e1;
        } else {
            if (e1.left == e2) {
                e2.left = e1;
                if (e1P.left == e1) {
                    e1P.left = e2;
                } else {
                    e1P.right = e2;
                }
            } else if (e2.right == e1) {
                e1.right = e2;
                if (e2P.left == e2) {
                    e2P.left = e1;
                } else {
                    e2P.right = e1;
                }
            } else {
                if (e1P.left == e1) {
                    e1P.left = e2;
                    if (e2P.left == e2) {
                        e2P.left = e1;
                    } else {
                        e2P.right = e1;
                    }
                } else {
                    e1P.right = e2;
                    if (e2P.left == e2) {
                        e2P.left = e1;
                    } else {
                        e2P.right = e1;
                    }
                }
            }
        }
        return head;
    }

    //测试
    public static void main(String[] args) {
        Chapter3_10 chapter = new Chapter3_10();
        Node head = new Node(3);
        head.left = new Node(5);
        head.right = new Node(4);
        head.left.left = new Node(1);
        head.right.right = new Node(2);
        Node[] errNode = chapter.getTwoErrNode(head);
        Node errNode1 = errNode[0];
        Node errNode2 = errNode[1];

        System.out.println("中序数组{1, 5, 3, 4, 2}中错误节点：" + errNode1.value + " 和 " + errNode2.value);
        Node[] errParents = chapter.getTwoErrParents(head, errNode1, errNode2);
        Node err1P = errParents[0];
        Node err2P = errParents[1];

        System.out.println("错误节点 " + errNode1.value + " 的父节点：" + (err1P == null ? "" : err1P.value));
        System.out.println("错误节点 " + errNode2.value + " 的父节点：" + (err2P == null ? "" : err2P.value));
        System.out.println("调整错误节点错误节点：" + errNode1.value + " 和 " + errNode2.value);
        head = chapter.adjustTree(head);
        System.out.print("调整后节点的中序遍历：");
        NodeUtil.inOrder(head);
    }

}

结果

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做个稳妥的人，不要高估两年内的自己，也不要低估十年后的自己。