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:
1
2
3
4
5
6
首先一个问题是怎么in-place flatten tree to a linkedlist?
应该给个提示就是 node.right ~~ node.next
ref http://www.cnblogs.com/springfor/p/3864355.html
public void flatten(TreeNode root) { if(root==null || (root.left==null && root.right==null)) return; Stack<TreeNode> st = new Stack<TreeNode>(); TreeNode n = root; while(n!=null || !st.isEmpty()){ if(n.right!=null){ st.push(n.right); } if(n.left!=null){ n.right = n.left; n.left=null; }else if(!st.isEmpty()){ TreeNode tmp=st.pop(); n.right=tmp; } n=n.right; } }
Flatten Binary Tree to Linked List
原文：http://www.cnblogs.com/jiajiaxingxing/p/4565056.html