Path Sum

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution(object):
    def hasPathSum(self, root, targetSum):
        """
        :type root: Optional[TreeNode]
        :type targetSum: int
        :rtype: bool
        """
        # If root is None, there is no path, return False
        if not root:
            return False
        
        # Subtract the current node's value from targetSum
        targetSum -= root.val
        
        # Check if we have reached a leaf node and the targetSum is now 0
        if not root.left and not root.right:
            return targetSum == 0
        
        # Recursively check the left and right subtrees
        return self.hasPathSum(root.left, targetSum) or self.hasPathSum(root.right, targetSum)