# Tree Pruning

Given a binary tree `root`

, prune the tree so that subtrees containing all `0`

s are removed.

**Constraints**

`n ≤ 100,000`

where`n`

is the number of nodes in`root`

https://binarysearch.com/problems/Tree-Pruning

## Examples

### Example 1

**Input**

- root =

**Output**

- answer =

**Explanation**

We do not remove the tree at the root or its right child because they still have a `1`

as a descendant.

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