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] 
- The binary tree will have at most
100 nodes. - The value of each node will only be
0or1.
# Definition for a binary tree node.# class TreeNode:# def __init__(self, x):# self.val = x# self.left = None# self.right = NoneclassSolution: defpruneTree(self, root: TreeNode) ->TreeNode: ifnotroot: returnNoneroot.left=self.pruneTree(root.left) root.right=self.pruneTree(root.right) ifroot.val==1orroot.leftorroot.right: returnrootelse: returnNone# Definition for a binary tree node.# class TreeNode# attr_accessor :val, :left, :right# def initialize(val = 0, left = nil, right = nil)# @val = val# @left = left# @right = right# end# end# @param {TreeNode} root# @return {TreeNode}defprune_tree(root)returnnilifroot.nil?root.left=prune_tree(root.left)root.right=prune_tree(root.right)ifroot.val == 1or not root.left.nil?or not root.right.nil?returnrootelsereturnnilendend