Added sudoku solver challenge

Author: imattman

09-sudoku/README.md

@@ -0,0 +1,39 @@
+# Challenge: Sudoku Solver
+
+Write a program that reads in an unsolved [sudoku puzzle][sudoku] and prints the solved puzzle.  
+
+Unsolved locations in the puzzle are represented by `_`.
+The input may be read in from a file or STDIN (your choice).
+
+Your program should print the solved puzzle in the same format but with the `_` empty slots filled in.
+
+Example input:
+
+    1 _ 3 _ _ 6 _ 8 _
+    _ 5 _ _ 8 _ 1 2 _
+    7 _ 9 1 _ 3 _ 5 6
+    _ 3 _ _ 6 7 _ 9 _
+    5 _ 7 8 _ _ _ 3 _
+    8 _ 1 _ 3 _ 5 _ 7
+    _ 4 _ _ 7 8 _ 1 _
+    6 _ 8 _ _ 2 _ 4 _
+    _ 1 2 _ 4 5 _ 7 8
+
+Example solution:
+
+    1 2 3 4 5 6 7 8 9
+    4 5 6 7 8 9 1 2 3
+    7 8 9 1 2 3 4 5 6
+    2 3 4 5 6 7 8 9 1
+    5 6 7 8 9 1 2 3 4
+    8 9 1 2 3 4 5 6 7
+    3 4 5 6 7 8 9 1 2
+    6 7 8 9 1 2 3 4 5
+    9 1 2 3 4 5 6 7 8
+
+This is a problem that can be solved using exhaustive brute force or more sophisticated rules and data handling.   How you go about it is up to you!  :-)
+
+*This challenge is shamelessly stolen from a [similar challenge][golang_challenge] in the Go community.*
+
+[sudoku]: https://en.wikipedia.org/wiki/Sudoku
+[golang_challenge]: http://golang-challenge.org/go-challenge8/

README.md

@@ -11,6 +11,7 @@ These are some additional coding challenges to sharpen your Python programming s
 0. [A Grep Clone](https://github.com/PDXPythonPirates/code-challenges/tree/master/06-pygrep/)
 0. [Connect Four](https://github.com/PDXPythonPirates/code-challenges/tree/master/07-connect-four/)
 0. [Check the Weather](https://github.com/PDXPythonPirates/code-challenges/tree/master/08-weather-check/)
+0. [Sudoku Solver](https://github.com/PDXPythonPirates/code-challenges/tree/master/09-sudoku/)
 
 
 ## How to Contribute