def tree_Coords(root, d, radius, level): if not root: return if level not in d.keys(): d[level] = dict() d[level].update({radius: root.info}) tree_Coords(root.left, d, radius-1, level+1) tree_Coords(root.right, d, radius+1, level+1)

def topView(root): radius = 0 level = 0 if not root: return d = dict() tree_Coords(root, d, radius, level) res = dict()

# Nested loop scans and adds values to res when no value exists for
# a specific radius. If raidus index already exists in res, then there existed
# another value with the same radius on a previous level(above).
for level in d.keys():
    for radius in d[level].keys():
        if radius not in res.keys():
            res[radius] = d[level][radius]

for r in sorted(res.keys()):
    print(res[r], end=" ")