class Solution(object):
def hasPathSum(self, root, sum):
"""
:type root: TreeNode
:type sum: int
:rtype: bool
"""
if root==None: return False
if root.left==None and root.right==None:
if root.val==sum: return True
else: return False
return self.hasPathSum(root.left, sum-root.val) or self.hasPathSum(root.right, sum-root.val)