Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.


For example:
Given the below binary tree and sum = 22,

              5
             / \
            4   8
           /   / \
          11  13  4
         /  \      \
        7    2      1



return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
from collections import deque
class Solution(object):
    def hasPathSum(self, root, sum):
        """
        :type root: TreeNode
        :type sum: int
        :rtype: bool
        """
        if root:
            queue = deque([(root, root.val)])
            while queue:
                p, s = queue.popleft()
                left, right = p.left, p.right
                if left:
                    queue.append((p.left, s + p.left.val))
                if right:
                    queue.append((p.right, s + p.right.val))
                if not left and not right and s == sum:
                    return True
            return False
        return False