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last fixes: tree common ancestor

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This commit is contained in:
Mari Wahl 2015-01-10 19:20:16 -05:00
parent cc8f1099d6
commit faa442ccb5
4 changed files with 109 additions and 53 deletions
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21
src/trees/binary_search_tree.py
View File

@ -54,10 +54,22 @@ class Node(object):
print self.item
if self.left:
return self.left._printPreorder()
self.left._printPreorder()
if self.right:
return self.right._printPreorder()
self.right._printPreorder()
# Another possibility: use an array (a little bit more expensive):
def _preorder_array(self):
nodes = []
if self.item:
nodes.append(self.item)
if self.left:
nodes.extend(self.left._preorder_array())
if self.right:
nodes.extend(self.right._preorder_array())
return nodes
@ -80,6 +92,11 @@ class BST(object):
if self.root:
return self.root._search(value)
def preorder_array(self):
if self.root:
return self.root._preorder_array()
else:
return 'Tree is empty.'
if __name__ == '__main__':

45
src/trees/binary_tree.py
View File

@ -47,6 +47,14 @@ class Node(object):
return not self.right and not self.left
def _preorder(self):
print self.item
if self.left:
self.left._preorder()
if self.right:
self.right._preorder()
class BT(object):
@ -61,40 +69,14 @@ class BT(object):
self.root._add(value)
def printPreorder(self):
current = self.root
nodes, stack = [], []
while stack or current:
if current:
nodes.append(current.item) # this is what change
stack.append(current)
current = current.left
else:
current = stack.pop()
current = current.right
print nodes
def printInorder(self):
current = self.root
nodes, stack = [], []
while stack or current:
if current:
stack.append(current)
current = current.left
else:
current = stack.pop()
nodes.append(current.item) # this is what change
current = current.right
print nodes
def search(self, value):
if self.root:
return self.root._search(value)
def preorder(self):
if self.root:
return self.root._preorder()
if __name__ == '__main__':
@ -111,7 +93,4 @@ if __name__ == '__main__':
print
print "Printing preorder..."
bt.printPreorder()
print "Printing Inorder..."
bt.printInorder()
bt.preorder()

51
src/trees/binary_tree_generators.py
View File

@ -14,14 +14,22 @@ class Node(object):
if not self.value:
self.value = new_node
elif not self.left:
self.left= new_node
self.left = new_node
elif not self. right:
self.right = new_node
else:
self.left = self.left.add(value)
return self # without this, it doesn't add!
def search(self, item):
if self.value == item:
return True
found = False
if (self.left and self.left.search(item)) or \
(self.right and self.right.search(item)):
found = True
return found
def preorder(self):
yield self.value
if self.left:
@ -40,7 +48,6 @@ class Node(object):
for node in self.right.postorder():
yield node
def inorder(self):
yield self.value
if self.left:
@ -50,6 +57,14 @@ class Node(object):
for node in self.right.inorder():
yield node
# this is the most basic way to write this function
def preorder_simple(self):
print self.value
if self.left:
self.left.preorder_simple()
if self.right:
self.right.preorder_simple()
# Another possibility: use an array (a little bit more expensive):
def preorder_array(self):
@ -74,6 +89,12 @@ class BT(object):
else:
self.root.add(value)
def search(self, item):
if self.root:
return self.root.search(item)
else:
return 'Tree is empty.'
def preorder(self):
if self.root:
return self.root.preorder()
@ -98,6 +119,11 @@ class BT(object):
else:
return 'Tree is empty.'
def preorder_simple(self):
if self.root:
return self.root.preorder_simple()
else:
return 'Tree is empty.'
if __name__ == '__main__':
@ -106,21 +132,38 @@ if __name__ == '__main__':
for i in range(1, 11):
tree.add(i)
print 'Searching for node 4'
print tree.search(4)
print 'Searching for node 1'
print tree.search(1)
print 'Searching for node 12'
print tree.search(12)
print 'Pre-order generator...'
getree = tree.preorder()
for i in range(10):
print next(getree)
print
print 'Pre-order array...'
print tree.preorder_array()
print
print 'Pre-order simple...'
tree.preorder_simple()
print
print 'Inorder...'
getree = tree.inorder()
for i in range(10):
print next(getree)
print
print 'Postorder...'
getree = tree.postorder()
for i in range(10):

45
src/trees/check_ancestor.py
View File

@ -4,37 +4,54 @@ __author__ = "bt3"
from binary_search_tree import BST, Node
from transversal import inorder
def find_ancestor(path, low_value, high_value):
def find_ancestor(path, low_item, high_item):
while path:
current_value = path[0]
current_item = path[0]
if current_value < low_value:
if current_item < low_item:
try:
path = path[2:]
except:
return current_value
return current_item
elif current_value > high_value:
elif current_item > high_item:
try:
path = path[1:]
except:
return current_value
return current_item
elif low_item <= current_item <= high_item:
return current_item
def find_ancestor2(tree, n1, n2):
if not tree:
return False
if n1 <= tree.item and n2 >= tree.item or (not tree.left and not tree.right) :
return tree.item
if tree.left and (n1 < tree.item and n2 < tree.item):
return find_ancestor(tree.left, n1, n2) or tree.item
if tree.right and (n1 > tree.item and n2 > tree.item):
return find_ancestor(tree.right, n1, n2) or tree.item
elif low_value <= current_value <= high_value:
return current_value
if __name__ == '__main__':
bst = BST()
l = [10, 5, 6, 3, 8, 2, 1, 11, 9, 4]
for i in l:
bst.add(i)
nodes = inorder(bst.root)
nodes = bst.preorder_array()
print 'Original: ', l
print 'Inorder: ', nodes
print 'Preorder: ', nodes
print 'Method 1: '
print 'Ancestor for 3, 11:', find_ancestor(nodes, 3, 11)
print 'Method 2: '
print 'Ancestor for 3, 11: ', find_ancestor2(bst.root, 3, 11)