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https://github.com/autistic-symposium/master-algorithms-py.git
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165 lines
3.6 KiB
Python
165 lines
3.6 KiB
Python
#!/usr/bin/python
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__author__ = "bt3"
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from collections import deque
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class Node(object):
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def __init__(self, item=None):
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self.item = item
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self.left = None
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self.right = None
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def _add(self, value):
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new_node = Node(value)
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if not self.item:
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self.item = new_node
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else:
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if value > self.item:
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self.right = self.right and self.right._add(value) or new_node
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elif value < self.item:
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self.left = self.left and self.left._add(value) or new_node
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else:
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print("BSTs do not support repeated items.")
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return self
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def _search(self, value):
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if self.item == value:
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return True
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elif self.left and value < self.item:
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return self.left._search(value)
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elif self.right and value > self.item:
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return self.right._search(value)
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else:
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return False
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def _isLeaf(self):
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return not self.right and not self.left
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def _printPreorder(self):
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print self.item
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if self.left:
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self.left._printPreorder()
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if self.right:
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self.right._printPreorder()
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def _preorder_array(self):
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nodes = []
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if self.item:
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nodes.append(self.item)
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if self.left:
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nodes.extend(self.left._preorder_array())
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if self.right:
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nodes.extend(self.right._preorder_array())
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return nodes
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class BST(object):
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def __init__(self):
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self.root = None
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def add(self, value):
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if not self.root:
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self.root = Node(value)
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else:
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self.root._add(value)
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def printPreorder(self):
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if self.root:
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self.root._printPreorder()
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def search(self, value):
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if self.root:
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return self.root._search(value)
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def preorder_array(self):
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if self.root:
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return self.root._preorder_array()
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else:
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return 'Tree is empty.'
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def BFT(tree):
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current = tree.root
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nodes = []
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queue = deque()
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queue.append(current)
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while queue:
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current = queue.popleft()
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nodes.append(current.item)
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if current.left:
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queue.append(current.left)
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if current.right:
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queue.append(current.right)
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return nodes
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def preorder(tree, nodes=None):
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nodes = nodes or []
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if tree:
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nodes.append(tree.item)
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if tree.left:
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preorder(tree.left, nodes)
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if tree.right:
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preorder(tree.right, nodes)
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return nodes
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def postorder(tree, nodes=None):
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nodes = nodes or []
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if tree:
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if tree.left:
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nodes = postorder(tree.left, nodes)
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if tree.right:
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nodes = postorder(tree.right, nodes)
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nodes.append(tree.item)
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return nodes
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def inorder(tree, nodes=None):
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nodes = nodes or []
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if tree:
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if tree.left:
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nodes = inorder(tree.left, nodes)
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nodes.append(tree.item)
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if tree.right:
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nodes = inorder(tree.right, nodes)
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return nodes
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if __name__ == '__main__':
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bst = BST()
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l = [10, 5, 6, 3, 8, 2, 1, 11, 9, 4]
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for i in l:
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bst.add(i)
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print
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print "Searching for nodes 16 and 6:"
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print bst.search(16)
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print bst.search(6)
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print
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print 'Traversals:'
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print 'Original: ', l
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print 'Preorder: ', preorder(bst.root)
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print 'Postorder: ', postorder(bst.root)
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print 'Inorder: ', inorder(bst.root)
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print 'BSF: ', BFT(bst) |