add algrithm highlight

Author: ryo

python/README.md

@@ -1,2 +1,27 @@
 # Leetcode challenge in python
- learn basic data structure and practice in python
+ learn basic data structure and practice in python
+
+## data structure
+   * Queue [Link to python documentation](https://docs.python.org/3/library/queue.html)
+   * Stack
+   * List
+   * Dict(Map)
+   * Tree
+
+## algrithm highlight
+### binary tree dfs
+```python
+def preorder(root):
+    if root:
+        return [root.val] + preorder(root.left) + preorder(root.right) 
+    else:
+        return []
+```
+
+## Environment setup
+### python installation
+```bash
+    pipenv install
+    pipenv shell
+```
+