019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
49 lines
935 B
Python
49 lines
935 B
Python
from collections import deque
|
|
|
|
class Node(object):
|
|
def __init__(self, value, left=None, right=None):
|
|
self.value = value
|
|
self.left = left
|
|
self.right = right
|
|
|
|
def is_bst(self):
|
|
s = []
|
|
s.append((float('-inf'), self, float('inf')))
|
|
while s:
|
|
lo, node, hi = s.pop()
|
|
if lo <= node.value <= hi:
|
|
node.left and s.append((lo, node.left, node.value))
|
|
node.right and s.append((node.value, node.right, hi))
|
|
else:
|
|
return False
|
|
return True
|
|
|
|
|
|
x = Node(
|
|
50,
|
|
Node(
|
|
17,
|
|
Node(
|
|
12,
|
|
Node(9),
|
|
Node(14),
|
|
),
|
|
Node(
|
|
23,
|
|
Node(19),
|
|
),
|
|
),
|
|
Node(
|
|
72,
|
|
Node(
|
|
54,
|
|
None,
|
|
Node(67)
|
|
),
|
|
Node(76),
|
|
),
|
|
)
|
|
|
|
|
|
assert x.is_bst()
|
|
print("Success!")
|