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Binary Tree Upside Down.java
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Binary Tree Upside Down.java
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/*
Given a binary tree where all the right nodes are either leaf nodes with a sibling (a left node that shares the same parent node)
or empty, flip it upside down and turn it into a tree where the original right nodes turned into left leaf nodes. Return the new
root.
Link: https://leetcode.com/problemset/algorithms/
Example:
For example:
Given a binary tree {1,2,3,4,5},
1
/ \
2 3
/ \
4 5
return the root of the binary tree [4,5,2,#,#,3,1].
4
/ \
5 2
/ \
3 1
Solution: None
Source: http://blog.csdn.net/whuwangyi/article/details/43186045
*/
public TreeNode UpsideDownBinaryTree(TreeNode root) {
if (root == null) {
return null;
}
TreeNode parent = root, left = root.left, right = root.right;
if (left != null) {
TreeNode ret = UpsideDownBinaryTree(left);
left.left = right;
left.right = parent;
return ret;
}
return root;
}