fix few details, binary search trees

src/trees/binary_search_tree.py

@@ -0,0 +1,73 @@
+#!/usr/bin/python
+
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
+from binary_tree import NodeBT, BinaryTree
+
+
+class NodeBST(NodeBT):
+
+    def __init__(self, item=None, level=0):
+        self.item = item
+        self.level = level
+        self.left = None
+        self.right = None
+
+
+    def _addNextNode(self, value, level_here=1):
+        new_node = NodeBST(value, level_here)
+        if not self.item:
+            self.item = new_node
+        else:
+            if value > self.item:
+                self.right = self.right and self.right._addNextNode(value, level_here+1) or new_node
+            elif value < self.item:
+                self.left = self.left and self.left._addNextNode(value, level_here+1) or new_node
+            else:
+                print("BSTs do not support repeated items.")
+        return self # this is necessary!!!
+
+
+
+    def _searchForNode(self, value):
+        if self.item == value:
+            return self
+        elif self.left and value < self.item:
+                return self.left._searchForNode(value)
+        elif self.right and value > self.item:
+                return self.right._searchForNode(value)
+        else:
+            return False
+
+
+
+class BinarySearchTree(BinaryTree):
+
+    def __init__(self):
+        self.root = None
+
+    def addNode(self, value):
+        if not self.root:
+            self.root = NodeBST(value)
+        else:
+            self.root._addNextNode(value)
+
+
+
+
+if __name__ == '__main__':
+    bst = BinarySearchTree()
+    print "Adding nodes 1 to 10 in the tree..."
+    for i in range(1, 10):
+        bst.addNode(i)
+    print "Is 8 a leaf? ", bst.isLeaf(8)
+    print "Whats the level of node 8? ", bst.getNodeLevel(8)
+    print "Is node 10 a root? ", bst.isRoot(10)
+    print "Is node 1 a root? ", bst.isRoot(1)
+    print "Whats the tree height? ", bst.getHeight()
+    print "Is this tree BST? ", bst.isBST()
+    print "Is this tree balanced? ", bst.isBalanced()
+
+