Added binary search tree challenge.

graphs_trees/bst/bst.py

@@ -0,0 +1,53 @@
+from collections import deque
+
+
+class Node(object):
+
+    def __init__(self, data):
+        self.data = data
+        self.left = None
+        self.right = None
+
+    def insert(self, data):
+        if data <= self.data:
+            if self.left is None:
+                self.left = Node(data)
+            else:
+                self.left.insert(data)
+        else:
+            if self.right is None:
+                self.right = Node(data)
+            else:
+                self.right.insert(data)
+
+    def in_order_traversal(self, visit_func):
+        if self.left is not None:
+            self.left.in_order_traversal(visit_func)
+        visit_func(self.data)
+        if self.right is not None:
+            self.right.in_order_traversal(visit_func)
+
+    def pre_order_traversal(self, visit_func):
+        visit_func(self.data)
+        if self.left is not None:
+            self.left.pre_order_traversal(visit_func)
+        if self.right is not None:
+            self.right.pre_order_traversal(visit_func)
+
+    def post_order_traversal(self, visit_func):
+        if self.left is not None:
+            self.left.post_order_traversal(visit_func)
+        if self.right is not None:
+            self.right.post_order_traversal(visit_func)
+        visit_func(self.data)
+
+    def bfs(self, visit_func):
+        queue = deque()
+        queue.append(self)
+        while len(queue) > 0:
+            node = queue.popleft()
+            visit_func(node.data)
+            if node.left is not None:
+                queue.append(node.left)
+            if node.right is not None:
+                queue.append(node.right)