Given a binary tree, flatten it to a linked list in-place.
For example,
Given
1
/ 2 5
/ \ 3 4 6
The flattened tree should look like:
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5
6
method 1 recursive method:
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public class Solution { public
void flatten(TreeNode root) { if(root != null){ TreeNode aNode = root.left; if(aNode != null){ while(aNode.right != null) aNode = aNode.right; aNode.right = root.right; root.right = root.left; root.left = null; } root = root.right; flatten(root); } }} |
method2: preorder tree traversal method
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public class Solution { public
void flatten(TreeNode root) { Stack<TreeNode> nodes = new
Stack<TreeNode>(); if(root != null){ TreeNode currentNode = root; if(root.right != null) nodes.push(root.right); if(root.left != null){ nodes.push(root.left); root.left = null; } while(!nodes.isEmpty()){ TreeNode aNode = nodes.pop(); currentNode.right = aNode; //currentNode.left = null; currentNode = currentNode.right; if(aNode.right != null) nodes.push(aNode.right); if(aNode.left != null){ nodes.push(aNode.left); aNode.left = null; } } } }} |
leetcode--Flatten Binary Tree to Linked List,布布扣,bubuko.com
leetcode--Flatten Binary Tree to Linked List
原文：http://www.cnblogs.com/averillzheng/p/3785045.html