Given a 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 1 right child.

Example 1:
Input: [5,3,6,2,4,null,8,1,null,null,null,7,9]

       5
      /\
    3    6
   / \\
  2   4    8
 /        /\
1        7   9

Output: [1,null,2,null,3,null,4,null,5,null,6,null,7,null,8,null,9]

 1\
   2\
     3\
       4\
         5\
           6\
             7\
               8\
                 9

Note:

1. The number of nodes in the given tree will be between 1 and 100.
2. Each node will have a unique integer value from 0 to 1000.

Github 同步地址:

https://github.com/grandyang/leetcode/issues/897

参考资料：

https://leetcode.com/problems/increasing-order-search-tree/

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