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binary_search_tree.py
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223 lines (196 loc) · 6.39 KB
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import unittest
class TreeNode(object):
def __init__(self, value):
self.value = value
self.left = None
self.right = None
def is_leaf(self):
return not self.left and not self.right
def has_left(self):
return not (self.left is None)
def has_right(self):
return not (self.right is None)
def children_count(self):
count = 0
if self.left is not None:
count += 1
if self.right is not None:
count += 1
return count
class BinarySearchTree(object):
def __init__(self):
self.root = None
def get_root(self):
return self.root
def add(self, value):
if self.root is None:
self.root = TreeNode(value)
else:
if self.find(value) is not None:
print('Duplicated value: ', value)
return
self._add(value, self.root)
def _add(self, value, node):
if value < node.value:
if node.left is not None:
self._add(value, node.left)
else:
node.left = TreeNode(value)
else:
if node.right is not None:
self._add(value, node.right)
else:
node.right = TreeNode(value)
def find(self, value):
if self.root is not None:
return self._find(value, self.root)
else:
return None
def _find(self, value, node):
if value == node.value:
return node
elif value < node.value and node.left is not None:
return self._find(value, node.left)
elif value > node.value and node.right is not None:
return self._find(value, node.right)
else:
return None
def init_tree(self):
self.root = None
def delete(self, value):
self.root, deleted = self._delete_value(self.root, value)
return deleted
def _delete_value(self, node, value):
if node is None:
return node, False
if value == node.value:
deleted = True
if node.left and node.right:
# replace the node to the leftmost of node.right
parent, child = node, node.right
while child.left is not None:
parent, child = child, child.left
child.left = node.left
if parent != node:
parent.left = child.right
child.right = node.right
node = child
elif node.left or node.right:
node = node.left or node.right
else:
node = None
elif value < node.value:
node.left, deleted = self._delete_value(node.left, value)
else:
node.right, deleted = self._delete_value(node.right, value)
return node, deleted
def print_tree(self):
if self.root is not None:
self._print_tree(self.root)
def _print_tree(self, node):
if node is not None:
self._print_tree(node.left)
print(str(node.value) + ' ')
self._print_tree(node.right)
def traverse(self, order='in'):
result = []
if self.root is not None:
if order == 'in':
self._in_order(self.root, result)
elif order == 'pre':
self._pre_order(self.root, result)
elif order == 'post':
self._post_order(self.root, result)
return result
def _in_order(self, node, result):
if node.left is not None:
self._in_order(node.left, result)
result.append(node.value)
if node.right is not None:
self._in_order(node.right, result)
def _pre_order(self, node, result):
result.append(node.value)
if node.left is not None:
self._pre_order(node.left, result)
if node.right is not None:
self._pre_order(node.right, result)
def _post_order(self, node, result):
if node.left is not None:
self._post_order(node.left, result)
if node.right is not None:
self._post_order(node.right, result)
result.append(node.value)
class TestBinaryTree(unittest.TestCase):
def test(self):
tree = BinarySearchTree()
tree.add(4)
tree.add(5)
tree.add(0)
tree.add(-1)
tree.add(8)
tree.add(2)
tree.add(1)
tree.add(3)
tree.add(4)
tree.print_tree()
self.assertEqual(tree.find(-1).value, -1)
self.assertEqual(tree.find(0).value, 0)
self.assertEqual(tree.find(1).value, 1)
self.assertEqual(tree.find(2).value, 2)
self.assertEqual(tree.find(3).value, 3)
self.assertEqual(tree.find(4).value, 4)
self.assertEqual(tree.find(5).value, 5)
self.assertEqual(tree.find(8).value, 8)
self.assertEqual(tree.find(-2), None)
self.assertEqual(tree.find(10), None)
self.assertEqual(
tree.traverse(order='in'),
[-1, 0, 1, 2, 3, 4, 5, 8]
)
self.assertEqual(
tree.traverse(order='pre'),
[4, 0, -1, 2, 1, 3, 5, 8]
)
self.assertEqual(
tree.traverse(order='post'),
[-1, 1, 3, 2, 0, 8, 5, 4]
)
self.assertTrue(tree.delete(4))
self.assertEqual(
tree.traverse(order='in'),
[-1, 0, 1, 2, 3, 5, 8]
)
self.assertTrue(tree.delete(8))
self.assertEqual(
tree.traverse(order='in'),
[-1, 0, 1, 2, 3, 5]
)
self.assertTrue(tree.delete(0))
self.assertEqual(
tree.traverse(order='in'),
[-1, 1, 2, 3, 5]
)
self.assertTrue(tree.delete(3))
self.assertEqual(
tree.traverse(order='in'),
[-1, 1, 2, 5]
)
self.assertTrue(tree.delete(2))
self.assertEqual(
tree.traverse(order='in'),
[-1, 1, 5]
)
self.assertTrue(tree.delete(-1))
self.assertTrue(tree.delete(1))
self.assertEqual(
tree.traverse(order='in'),
[5]
)
self.assertTrue(tree.delete(5))
self.assertEqual(
tree.traverse(order='in'),
[]
)
self.assertFalse(tree.delete(0))
if __name__ == '__main__':
unittest.TestCase()