Solution to day 9, in lex.

2017/README.md

@@ -16,6 +16,7 @@ The current plan, in no particular order:
 - [ ] Haskell
 - [ ] Java
 - [ ] Kotlin
+- [x] Lex - [Day 09](./day-09/solution.l)
 - [x] Matlab - [Day 06](./day-06)
 - [ ] Node.js
 - [ ] Objective C

2017/day-09/.gitignore

@@ -0,0 +1 @@
+solution

2017/day-09/Makefile

@@ -0,0 +1,3 @@
+CFLAGS=-Wall -Wextra
+
+all: solution

2017/day-09/solution.l

@@ -0,0 +1,30 @@
+%{
+#include <stdio.h>
+
+int nest = 0;
+int score = 0;
+int garbage = 0;
+%}
+%x GARBAGE
+%%
+\{ ++nest;
+\} score += nest--;
+, ;
+\< BEGIN GARBAGE;
+
+<GARBAGE>!. ;
+<GARBAGE>\> BEGIN 0;
+<GARBAGE>. ++garbage;
+
+%%
+
+int yywrap()
+{
+	return 1;
+}
+
+int main()
+{
+	yylex();
+	printf("Groups: %d\nGarbage: %d\n", score, garbage);
+}