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814. Binary Tree Pruning

We are given the head node root of a binary tree, where additionally every node's value is either a 0 or a 1.

Return the same tree where every subtree (of the given tree) not containing a 1 has been removed.

(Recall that the subtree of a node X is X, plus every node that is a descendant of X.)

Example 1:
Input: [1,null,0,0,1]
Output: [1,null,0,null,1]
 
Explanation: 
Only the red nodes satisfy the property "every subtree not containing a 1".
The diagram on the right represents the answer.


Example 2:
Input: [1,0,1,0,0,0,1]
Output: [1,null,1,null,1]



Example 3:
Input: [1,1,0,1,1,0,1,0]
Output: [1,1,0,1,1,null,1]



Note:

  • The binary tree will have at most 200 nodes.
  • The value of each node will only be 0 or 1.

Difficulty:

Medium

Lock:

Normal

Company:

Capital One Hulu Twitter