Path-Sum.py

class Solution:
    def hasPathSum(self, root: TreeNode, sum: int) -> bool:
        if root is None:
            return False
        isLeaf = (root.left==None) and (root.right==None)
        sum -= root.val
        if isLeaf:
            return sum == 0
        return self.hasPathSum(root.left, sum) or self.hasPathSum(root.right, sum)