added Tree creation and traversal

Author: Tanmay-901

tree/BFS_preorder_traversal.py

@@ -0,0 +1,25 @@
+class TreeNode:
+    def __init__(self, data):
+        self.data = data
+        self.lnode = None
+        self.rnode = None
+
+
+def preOrderTraversal(rootNode):
+    if not rootNode:
+        return
+    print(rootNode.data)
+    preOrderTraversal(rootNode.lnode)
+    preOrderTraversal(rootNode.rnode)
+
+
+bt = TreeNode("Drinks")
+leftchild = TreeNode("hot")
+rightchild = TreeNode("cold")
+hotchild = TreeNode("Tea")
+coldchild = TreeNode("Cola")
+leftchild.lnode = hotchild
+rightchild.rnode = coldchild
+bt.lnode = leftchild
+bt.rnode = rightchild
+preOrderTraversal(bt)

tree/create_tree.py

@@ -0,0 +1,30 @@
+class TreeNode:
+    def __init__(self, data, children=[]):
+        self.data = data
+        self.children = children
+
+    def __str__(self, level=0):
+        ret = "  " * level + str(self.data) + "\n"
+        for child in self.children:
+            ret += child.__str__(level+1)
+        return ret
+
+    def addchild(self, TreeNode):
+        self.children.append(TreeNode)
+
+
+tree = TreeNode('Drinks', [])
+cold = TreeNode('Cold', [])
+hot = TreeNode('Hot', [])
+tree.addchild(hot)
+tree.addchild(cold)
+coffee = TreeNode('Coffee', [])
+tea = TreeNode('Tea', [])
+cola = TreeNode('Cola', [])
+fanta = TreeNode('Fanta', [])
+cold.addchild(cola)
+cold.addchild(fanta)
+hot.addchild(tea)
+hot.addchild(coffee)
+
+print(tree)