reorganize dir

Signed-off-by: Mia Steinkirch <mia.steinkirch@gmail.com>

ebook_src/trees/check_ancestor.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+
+from binary_search_tree import BST, Node
+
+def find_ancestor(path, low_item, high_item):
+    while path:
+        current_item = path[0]
+
+        if current_item < low_item:
+            try:
+                path = path[2:]
+            except:
+                return current_item
+
+        elif current_item > high_item:
+            try:
+                path = path[1:]
+            except:
+                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
+
+
+
+if __name__ == '__main__':
+    bst = BST()
+    l = [10, 5, 6, 3, 8, 2, 1, 11, 9, 4]
+    for i in l:
+        bst.add(i)
+    nodes = bst.preorder_array()
+
+    print 'Original:    ', l
+    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)