Top view of binary tree

    def topView(self,root):
        ans=deque()
        ans.appendleft(root.data)
        q=deque()
        q.append((root,0))#adding verticle line height in vertical order traversal
        l,r=0,0
        while q:
            t,d=q.popleft()
            if d<l:#if you have found left most vert line then add to left of deque
                l=d
                ans.appendleft(t.data)
            if d>r:#if you have found right most vert line then add to right of deque
                r=d
                ans.append(t.data)
            if t.left:q.append((t.left,d-1))
            if t.right:q.append((t.right,d+1))

        return ans