fix the image 💚

Author: Mari Wahl

README.md

@@ -2,7 +2,7 @@
 
 An introduction to Algorithms & Data Structures in Python, including an ["e-book" I wrote](http://mariwahl.us/docs/algorithms_in_python.pdf).
 
-![](http://i.imgur.com/XruamX1.png)
+![](http://i.imgur.com/MJZjABD.png)
 
 
 ---