112. Path Sum

Python

# 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 hasPathSum(self, root: Optional[TreeNode], targetSum: int) -> bool:
        if not root or root.val is None:
            return False
        if self.startFind(root, targetSum, 0):
            return True
        return False
    
    def startFind(self, root: Optional[TreeNode], targetSum: int,
                  total: int) -> bool:
        if not root.left and not root.right and total + root.val == targetSum:
            return True
        
        
        if root.left:
            if self.startFind(root.left, targetSum, total + root.val):
                return True
        if root.right:
            if self.startFind(root.right, targetSum, total + root.val):
                return True
        return False