Given the root of a binary tree, return the same tree where every subtree (of the given tree) not containing a 1 has been removed.
A subtree of a node node is node plus every node that is a descendant of node.
Example 1:
Input: root = [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: root = [1,0,1,0,0,0,1]
Output: [1,null,1,null,1]
Example 3:
Input: root = [1,1,0,1,1,0,1,0]
Output: [1,1,0,1,1,null,1]
Constraints:
- The number of nodes in the tree is in the range
[1, 200]. -
Node.valis either0or1.
SOLUTION:
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def hasOne(self, root):
if root:
if root.val == 1:
return True
if self.hasOne(root.left) or self.hasOne(root.right):
return True
return False
def pruneTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
if not self.hasOne(root):
return None
root.left = self.pruneTree(root.left)
root.right = self.pruneTree(root.right)
return root
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