USING: grouping io.encodings.utf8 io.files kernel math
math.ranges sequences sets ;
IN: aoc.3

: input ( -- i ) "~/factor/aoc/3/3.in" utf8 file-lines ;

: priorities ( -- p ) 97 122 [a,b] 65 90 [a,b] append ;

: intersection-score ( seq -- n ) intersection first priorities index 1 + ;

: part1 ( -- n ) input [ halves { } 2sequence intersection-score ] map-sum ;

: part2 ( -- n ) input 3 <groups> [ intersection-score ] map-sum ;