def _compose_ht_tree(self, text):
"""Huffman tree construction for text."""
freq_table = self._compute_chr_freq(text)
ht_queue = HeapPriorityQueue()
for freq, lett in freq_table:
ht_tree = LinkedBinaryTree()
ht_tree._add_root((freq, lett))
ht_queue.add(freq, ht_tree)
while len(ht_queue) > 1:
(freq1, subtree1) = ht_queue.remove_min()
(freq2, subtree2) = ht_queue.remove_min()
freq = freq1 + freq2
ht_tree = LinkedBinaryTree()
ht_tree._add_root((freq, None))
ht_tree._attach(ht_tree.root(), subtree1, subtree2)
ht_queue.add(freq, ht_tree)
_, ht_tree = ht_queue.remove_min()
return ht_tree
if T.left(p) is not None:
inorder(T.left(p))
print T._validate(p)._element
if T.right(p) is not None:
inorder(T.right(p))
if __name__ == '__main__':
import random
def build_tree(T, p, level):
if level > 5:
return None
else:
if T.left(p) is None:
T._add_left(p, random.randint(1, 10))
build_tree(T, T.left(p), level+1)
if T.right(p) is None:
T._add_right(p, random.randint(1, 10))
build_tree(T, T.right(p), level+1)
test_tree = LinkedBinaryTree()
test_tree._add_root('10')
build_tree(test_tree, test_tree.root(), 1)
count = 1
for x in test_tree.positions():
print str(count) +': ' + str(test_tree._validate(x)._element)
count += 1
"""Preorder traversal"""
# 应该使用普通的树而不是二叉树
from linked_binary_tree import LinkedBinaryTree
# Electronics R’Us
# 1 R&D
# 2 Sales
# 2.1 Domestic
# 2.2 International
# 2.2.1 Canada
# 2.2.2 America
toc = LinkedBinaryTree()
toc._add_root('Electronics R’Us')
toc._add_left(toc.root(), 'R&D')
toc._add_right(toc.root(), 'Sales')
toc._add_left(toc.right(toc.root()), 'Domestic')
toc._add_right(toc.right(toc.root()), 'International')
toc._add_left(toc.right(toc.right(toc.root())), 'Canada')
toc._add_right(toc.right(toc.right(toc.root())), 'America')
def parenthesize(t, p, rep):
if t.is_empty():
return
rep += str(p.element())
if not t.is_leaf(p):
first_time = True
for c in t.children(p):
from linked_binary_tree import LinkedBinaryTree
a = LinkedBinaryTree()
print('!!!')
a._add_root('!!')
a._add_left(a.root(), '????')
print('!')
print(a.left(a.root()).element())
a._delete(a.left(a.root()))
def test_root(self):
blank_tree = LinkedBinaryTree()
root = blank_tree.root()
self.assertEqual(root, None) # Should return None for an empty tree.
root = self.tree.root()
self.assertEqual(root.element(), "Root")
class TestSimpleCases(unittest.TestCase):
"""
Test obvious cases to confirm basic functionality and syntax
correctness.
"""
def setUp(self):
self.tree = LinkedBinaryTree()
# Create a proper balanced tree with 3 levels (8 elements)
self.root = self.tree._add_root("Root")
self.left = self.tree._add_left(self.root, "L2 left child")
self.right = self.tree._add_right(self.root, "L2 right child")
self.lev3_first_left = self.tree._add_left(self.left, "L3 left-1")
self.tree._add_right(self.left, "L3 right-1")
self.tree._add_left(self.right, "L3 left-2")
self.tree._add_right(self.right, "L3 right-2")
def test_validate(self):
# Passing an object of type other than Position should raise TypeError
with self.assertRaises(TypeError):
self.tree._validate("spam")
# Wrong container should raise value error
position_from_other_container = LinkedBinaryTree()._add_root(
"spam root")
with self.assertRaises(ValueError):
self.tree._validate(position_from_other_container)
# If node was deprecated, meaning it was set to be its own parent per
# the internal convention for deprecated nodes, then should raise
# value error.
p = self.lev3_first_left
p._node._parent = p._node
with self.assertRaises(ValueError):
self.tree._validate(p)
# ---------------------------------- public methods --------------------
def test_root(self):
blank_tree = LinkedBinaryTree()
root = blank_tree.root()
self.assertEqual(root, None) # Should return None for an empty tree.
root = self.tree.root()
self.assertEqual(root.element(), "Root")
def test_parent(self):
# should return None when called on p = root
parent_of_root = self.tree.parent(self.tree.root())
self.assertEqual(parent_of_root, None)
parent_of_left = self.tree.parent(self.left) # Position object from
# setUp, name self.left references
# root's left child.
self.assertEqual(parent_of_left, self.root)
# Try the next level down
parent_of_node = self.tree.parent(self.lev3_first_left)
self.assertEqual(parent_of_node, self.left)
def test_left(self):
left = self.tree.left(self.root) # parent's left should be the object
# stored as self.left
self.assertEqual(left, self.left)
def test_right(self):
right = self.tree.right(self.root) # root's right should be the object
# stored as self.right
self.assertEqual(right, self.right)
def test_num_children(self):
self.assertEqual(self.tree.num_children(self.root),
2) # Root has 2 children
self.assertEqual(self.tree.num_children(self.right), 2) # Right has 2
self.assertEqual(self.tree.num_children(self.lev3_first_left),
0) # This node should be in the
# bottom level of the setUp
# tree and therefore have
# no children.
# ------------------- tests for concrete methods inherited from Tree ------
def test_is_root(self):
"""Concrete method implemented in the Tree abstract base class and
inherited through to LBT class."""
# Should be true for root
self.assertTrue(self.tree.is_root(self.root))
# Should be false for a node from the middle or bottom layer
self.assertFalse(self.tree.is_root(self.right))
self.assertFalse(self.tree.is_root(self.lev3_first_left))
def test_is_leaf(self):
# testing _attach will "coverage" this
pass
def test_is_empty(self):
# testing _attach will "coverage this
pass
def test_height(self):
"""
Test the height method defined in the Tree abstract base class
that LBT class has through inheritance.
"""
# Calling it on root should return 2, the height of the full three-level
# tree.
self.assertEqual(self.tree.height(self.root), 2)
# Height of a node in the middle layer should be 1
self.assertEqual(self.tree.height(self.right), 1)
# Height of a node in the bottom layer should be 0
self.assertEqual(self.tree.height(self.lev3_first_left), 0)
def test_depth(self):
"""
Test the depth method defined in the Tree abstract base class and
inherited in the LBT class.
"""
# Depth of a node in the bottom later should be 2 (2 levels separating
# that Position from root Position).
self.assertEqual(self.tree.depth(self.lev3_first_left), 2)
# Depth of node in middle layer should be 1
self.assertEqual(self.tree.depth(self.left), 1)
# Depth of root should be zero
self.assertEqual(self.tree.depth(self.root), 0)
def test_attach(self):
"""Tests for the nonpublic _attach method, mainly to hit inherited public
methods that it will call."""
new_tree = LinkedBinaryTree()
ntroot = new_tree._add_root("New tree root")
new_tree._add_left(ntroot, "NT left")
new_tree._add_right(ntroot, "NT right")
new_tree2 = LinkedBinaryTree()
nt2root = new_tree2._add_root("2nd new tree root")
new_tree2._add_left(nt2root, "left")
new_tree2._add_right(nt2root, "right")
self.tree._attach(self.lev3_first_left, new_tree, new_tree2)
# For now just pass if none of these calls raised an error, no
# unittest.assertSomething method call
def test_positions(self): # This covers postorder() method for purposes
# of the "coverage" metric.
for position in self.tree.positions(
): # Test that they can be iterated
self.assertIsInstance(position,
LinkedBinaryTree.Position) # and that
# they're all Positions
## def test_preorder(self): # placeholder
## pass
def test_postorder(self):
for position in self.tree.postorder():
self.assertIsInstance(position, LinkedBinaryTree.Position)
"""Preorder traversal"""
# 应该使用普通的树而不是二叉树
from linked_binary_tree import LinkedBinaryTree
# Electronics R’Us
# 1 R&D
# 2 Sales
# 2.1 Domestic
# 2.2 International
# 2.2.1 Canada
# 2.2.2 America
toc = LinkedBinaryTree()
toc._add_root('Electronics R’Us')
toc._add_left(toc.root(), 'R&D')
toc._add_right(toc.root(), 'Sales')
toc._add_left(toc.right(toc.root()), 'Domestic')
toc._add_right(toc.right(toc.root()), 'International')
toc._add_left(toc.right(toc.right(toc.root())), 'Canada')
toc._add_right(toc.right(toc.right(toc.root())), 'America')
# Solution 1: O(n^2)
# for p in toc.preorder():
# print(toc.depth(p)*2*' '+p.element())
# Solution 2: O(n)
def preorder_indent(t, p, d):
print(2 * d * ' ' + p.element())
for c in t.children(p):
preorder_indent(t, c, d + 1)
from linked_binary_tree import LinkedBinaryTree
# Construct Tree:
T = LinkedBinaryTree()
T.add_root(1)
p1 = T.add_left(T.root(), 2)
p2 = T.add_right(T.root(), 3)
T.add_left(p1, 4)
T.add_right(p1, 5)
p3 = T.add_left(p2, 6)
p4 = T.add_right(p2, 7)
T.add_left(p3, 8)
T.add_right(p3, 9)
T.add_right(p4, 10)
# Check Traversals:
print("\nPreorder: ")
for p in T.preorder():
print(p.element())
print("\nPostorder: ")
for p in T.postorder():
print(p.element())
print("\nInorder: ")
