40 lines
1.2 KiB
EmacsLisp
40 lines
1.2 KiB
EmacsLisp
;; Advent of Code 2020 - Day 6
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(require 'cl-lib)
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(require 'dash)
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(require 'f)
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(require 'ht)
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(require 's)
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(defvar day6/input (s-split "\n\n" (f-read "/tmp/aoc/day6.txt") t)
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"Input, split into groups (with people in each group still distinct)")
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;; Puzzle 1
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(defun day6/count-answers (group-answers)
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"I suspect doing it this way will be useful in puzzle 2."
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(let ((table (ht-create)))
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(-each group-answers
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(lambda (answer)
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(cl-loop for char across answer
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do (ht-set table char (+ 1 (or (ht-get table char)
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0))))))
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table))
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(message "Solution to day6/1: %s"
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(cl-loop for group being the elements of day6/input
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sum (length
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(ht-keys
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(day6/count-answers (s-lines group))))))
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;; Puzzle 2
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(defun day6/count-unanimous-answers (answers)
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(ht-reject (lambda (_key value) (not (= value (length answers))))
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(day6/count-answers answers)))
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(message "Solution to day6/2: %s"
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(cl-loop for group being the elements of day6/input
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sum (length
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(ht-keys
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(day6/count-unanimous-answers (s-split "\n" group t))))))
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