[Leetcode problem]: flatten binary tree to linked list

Given a binary tree, flatten it to a linked list in-place.

For example,
Given

 
1/2 5/\ 3 4 6
 

 

The flattened tree shoshould look like:

 
1 2 3 4 5 6
 

Hints:

If you notice carefully in the flattened tree, each node's right child points to the next node of a pre-order traversal.

 

Translate any binary tree into a binary tree with only a left subtree.

Requirements: (1) no additional storage space can be used for sorting and sorting.

(2) The modified tree is a binary tree with only the left subtree, And the node order is the first traversal of the original binary tree.

Idea: The result is first-order traversal, but the recursion method is post-order traversal.

 Class  Solution {  Public  :  Void Flatten (treenode * Root ){  If (Root = NULL) Return  ; Flatten (Root -> Left); flatten (Root -> Right );  If (Root-> left = NULL) Return ; Treenode * P = root-> Left;  While (P-> right) P = p-> Right; P -> Right = root-> Right; root -> Right = root-> Left; root -> Left = Null ;}}; 

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