message: Update path-sum-iv.py
diff: @@ -28,8 +28,7 @@ class Solution(object):
  child = Node(num)
  while not parent.isParent(child):
  result += parent.val if parent.leaf else 0
  - parent = q[0]
  - q.popleft()
  + parent = q.popleft()
  parent.leaf = False
  child.val += parent.val
  q.append(child)
  