Create sum_tree_nodes.py

Author: learning-zone

sum_tree_nodes.py

@@ -0,0 +1,48 @@
+def num_nodes(tree):
+    """Counts the number of nodes in a tree.
+
+        >>> class Node(object):
+        ...     def __init__(self, data):
+        ...             self.data=data
+        ...             self.children = []
+        ...     def add_child(self, obj):
+        ...             self.children.append(obj)
+        ...
+        >>> one = Node(1)
+        >>> two = Node(2)
+        >>> three = Node(3)
+        >>> one.add_child(two)
+        >>> one.add_child(three)
+        >>> num_nodes(one)
+        3
+        >>> four = Node(4)
+        >>> five = Node(5)
+        >>> two.add_child(four)
+        >>> two.add_child(five)
+        >>> num_nodes(one)
+        5
+        >>> six = Node(6)
+        >>> three.add_child(six)
+        >>> num_nodes(one)
+        6
+    """
+
+    nodes = 1
+
+    if tree is None:
+      return 0
+
+    for child in tree.children:
+      nodes += num_nodes(child)
+
+
+    return nodes
+
+
+
+if __name__ == "__main__":
+    import doctest
+    results = doctest.testmod()
+
+    if not results.failed:
+        print "ALL TESTS PASSED"