Created
July 16, 2016 20:39
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flatten - facebook code lab - flatten a tree
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/** | |
* Definition for binary tree | |
* class TreeNode { | |
* int val; | |
* TreeNode left; | |
* TreeNode right; | |
* TreeNode(int x) { val = x; } | |
* } | |
*/ | |
public class Solution { | |
public TreeNode flatten(TreeNode a) { | |
if(a==null) | |
return null; | |
TreeNode l_subtree = flatten(a.left); // | |
TreeNode r_subtree = flatten(a.right); | |
TreeNode lastNode = lastNode(l_subtree); | |
a.left = null; | |
a.right = l_subtree; | |
lastNode.right = r_subtree; | |
return a; | |
} | |
public TreeNode lastNode(TreeNode a) | |
{ | |
TreeNode lastNode = a; | |
while(lastNode !=null && | |
lastNode.right !=null) | |
{ | |
lastNode = lastNode.right; | |
} | |
return lastNode; | |
} | |
} |
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