019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
121 lines
3.8 KiB
Python
121 lines
3.8 KiB
Python
import unittest
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################################################################################
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# Implementation
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################################################################################
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# is_leaf :: Node(a) -> Boolean
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def is_leaf(node):
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return not node.left and not node.right
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# is_binary_search_tree :: Node(Integer) -> Set(Int) -> Set(Int) -> Boolean
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def is_binary_search_tree_a(node, la=set(), ra=set()):
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"""My first solution for this problem."""
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for x in la:
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if not node.value < x:
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return False
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for x in ra:
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if not node.value > x:
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return False
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if is_leaf(node):
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return True
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elif not node.left:
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return is_binary_search_tree(
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node.right,
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la=la,
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ra=ra ^ {node.value},
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)
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elif not node.right:
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return is_binary_search_tree(node.left, la=la ^ {node.value}, ra=ra)
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else:
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return all([
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is_binary_search_tree(node.left, la=la ^ {node.value}, ra=ra),
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is_binary_search_tree(node.right, la=la, ra=ra ^ {node.value})
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])
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# is_binary_search_tree :: Node(Int) -> Maybe(Int) -> Maybe(Int) -> Boolean
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def is_binary_search_tree(node, lb=None, ub=None):
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if lb:
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if node.value < lb:
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return False
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if ub:
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if node.value > ub:
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return False
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if is_leaf(node):
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return True
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elif not node.right:
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return is_binary_search_tree(node.left, lb=lb, ub=node.value)
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elif not node.left:
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return is_binary_search_tree(node.right, lb=node.value, ub=ub)
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else:
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return is_binary_search_tree(
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node.left, lb=lb, ub=node.value) and is_binary_search_tree(
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node.right, lb=node.value, ub=ub)
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################################################################################
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# Tests
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################################################################################
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class Test(unittest.TestCase):
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class BinaryTreeNode(object):
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def __init__(self, value):
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self.value = value
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self.left = None
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self.right = None
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def insert_left(self, value):
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self.left = Test.BinaryTreeNode(value)
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return self.left
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def insert_right(self, value):
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self.right = Test.BinaryTreeNode(value)
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return self.right
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def test_valid_full_tree(self):
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tree = Test.BinaryTreeNode(50)
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left = tree.insert_left(30)
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right = tree.insert_right(70)
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left.insert_left(10)
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left.insert_right(40)
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right.insert_left(60)
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right.insert_right(80)
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result = is_binary_search_tree(tree)
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self.assertTrue(result)
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def test_both_subtrees_valid(self):
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tree = Test.BinaryTreeNode(50)
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left = tree.insert_left(30)
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right = tree.insert_right(80)
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left.insert_left(20)
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left.insert_right(60)
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right.insert_left(70)
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right.insert_right(90)
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result = is_binary_search_tree(tree)
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self.assertFalse(result)
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def test_descending_linked_list(self):
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tree = Test.BinaryTreeNode(50)
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left = tree.insert_left(40)
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left_left = left.insert_left(30)
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left_left_left = left_left.insert_left(20)
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left_left_left.insert_left(10)
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result = is_binary_search_tree(tree)
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self.assertTrue(result)
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def test_out_of_order_linked_list(self):
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tree = Test.BinaryTreeNode(50)
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right = tree.insert_right(70)
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right_right = right.insert_right(60)
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right_right.insert_right(80)
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result = is_binary_search_tree(tree)
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self.assertFalse(result)
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def test_one_node_tree(self):
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tree = Test.BinaryTreeNode(50)
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result = is_binary_search_tree(tree)
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self.assertTrue(result)
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unittest.main(verbosity=2)
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