Increasing Order Search Tree
Given the root of a binary search tree, rearrange the tree in in-order so that the leftmost node in the tree is now the root of the tree, and every node has no left child and only one right child.
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Example 1:
Input: root = [5,3,6,2,4,null,8,1,null,null,null,7,9]
Output: [1,null,2,null,3,null,4,null,5,null,6,null,7,null,8,null,9]
Example 2:
Input: root = [5,1,7]
Output: [1,null,5,null,7]
Java Solution
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/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public TreeNode increasingBST(TreeNode root) {
return increasingBST(root, null);
}
public TreeNode increasingBST(TreeNode root, TreeNode tail) {
if (root == null) return tail;
TreeNode res = increasingBST(root.left, root);
root.left = null;
root.right = increasingBST(root.right, tail);
return res;
}
}
