LeetCode Flatten Binary Tree to Linked List

最新推荐文章于 2022-09-06 16:04:14 发布

转载最新推荐文章于 2022-09-06 16:04:14 发布 · 46 阅读

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原文链接：http://www.cnblogs.com/birdhack/p/4064010.html

本文介绍了一种将二叉树结构通过特定算法展平为链表的方法。通过递归方式处理二叉树的左右子节点，最终实现原地转换。此过程涉及到遍历二叉树、调整指针等步骤。

Given a binary tree, flatten it to a linked list in-place.

For example,
Given

The flattened tree should look like:

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public void flatten(TreeNode root) {
            if (root==null) {
                return;
            }
            if (root.left==null) {
                flatten(root.right);
                return;
            }

            TreeNode lefTreeNode=root.left;

            TreeNode righTreeNode=root.right;
            if (righTreeNode==null) {
                flatten(lefTreeNode);
                root.left=null;
                root.right=lefTreeNode;
                return;
            }
            if (lefTreeNode.left==null && 
                    lefTreeNode.right==null&& 
                    righTreeNode.right==null && 
                    righTreeNode.left==null) {
                root.left=null;
                root.right=lefTreeNode;
                lefTreeNode.right=righTreeNode;
                return;
                
            }
            
            flatten(lefTreeNode);
            flatten(righTreeNode);
            root.left=null;
            root.right=lefTreeNode;
            lefTreeNode.left=null;
            TreeNode node=lefTreeNode;
            while (node.right!=null) {
                node=node.right;
            }
            node.right=righTreeNode;
            return;
            
        
    }
}