mirror of
https://github.com/TheAlgorithms/Python.git
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131 lines
3.2 KiB
Python
131 lines
3.2 KiB
Python
'''
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A binary search Tree
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'''
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class Node:
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def __init__(self, label):
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self.label = label
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self.left = None
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self.right = None
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def getLabel(self):
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return self.label
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def setLabel(self, label):
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self.label = label
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def getLeft(self):
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return self.left
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def setLeft(self, left):
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self.left = left
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def getRight(self):
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return self.right
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def setRight(self, right):
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self.right = right
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class BinarySearchTree:
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def __init__(self):
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self.root = None
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def insert(self, label):
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# Create a new Node
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new_node = Node(label)
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# If Tree is empty
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if self.empty():
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self.root = new_node
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else:
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#If Tree is not empty
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parent_node = None
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curr_node = self.root
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#While we don't get to a leaf
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while curr_node is not None:
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#We keep reference of the parent node
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parent_node = curr_node
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#If node label is less than current node
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if new_node.getLabel() < curr_node.getLabel():
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#We go left
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curr_node = curr_node.getLeft()
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else:
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#Else we go right
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curr_node = curr_node.getRight()
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#We insert the new node in a leaf
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if new_node.getLabel() < parent_node.getLabel():
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parent_node.setLeft(new_node)
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else:
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parent_node.setRight(new_node)
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def getNode(self, label):
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curr_node = None
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#If the tree is not empty
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if(not self.empty()):
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#Get tree root
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curr_node = self.getRoot()
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#While we don't find the node we look for
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#I am using lazy evaluation here to avoid NoneType Attribute error
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while curr_node is not None and curr_node.getLabel() is not label:
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#If node label is less than current node
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if label < curr_node.getLabel():
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#We go left
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curr_node = curr_node.getLeft()
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else:
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#Else we go right
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curr_node = curr_node.getRight()
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return curr_node
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def empty(self):
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if self.root is None:
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return True
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return False
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def preShow(self, curr_node):
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if curr_node is not None:
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print(curr_node.getLabel())
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self.preShow(curr_node.getLeft())
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self.preShow(curr_node.getRight())
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def getRoot(self):
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return self.root
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'''
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Example
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8
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/ \
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3 10
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/ \ \
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1 6 14
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/ \ /
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4 7 13
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'''
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if __name__ == "__main__":
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t = BinarySearchTree()
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t.insert(8)
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t.insert(3)
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t.insert(1)
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t.insert(6)
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t.insert(4)
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t.insert(7)
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t.insert(10)
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t.insert(14)
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t.insert(13)
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t.preShow(t.getRoot())
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if(t.getNode(6) is not None):
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print("The label 6 exists")
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else:
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print("The label 6 doesn't exist")
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if(t.getNode(-1) is not None):
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print("The label -1 exists")
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else:
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print("The label -1 doesn't exist")
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