56 lines
1.4 KiB
Common Lisp
56 lines
1.4 KiB
Common Lisp
(defvar input (uiop:read-file-string "2-input"))
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;; Each newline represents a new round, which we should parse on the go
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(defun sensible-convert-input (str)
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(cond
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((or (string= str "X") (string= str "A")) 0)
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((or (string= str "Y") (string= str "B")) 1)
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((or (string= str "Z") (string= str "C")) 2)))
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;; Round 1
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(defvar rounds
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(with-input-from-string (stream input)
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(loop
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for strategy = (read-line stream nil)
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until (null strategy)
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collect
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(let ((opponent (subseq strategy 0 1))
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(yours (subseq strategy 2 3)))
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(list (sensible-convert-input opponent)
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(sensible-convert-input yours))))))
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(loop
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for round in rounds
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until (null round)
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sum
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(destructuring-bind (opp you) round
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(+
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1 you ;; base score
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(cond ; outcome score
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((eq you opp) 3)
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((eq (mod (+ 1 opp) 3) you) 6)
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(t 0)))))
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;; Round 2.
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;; We can still use the same rounds data as previously, just
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;; reinterpret it in when doing the sum.
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(defun get-correct-choice (opponent outcome)
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(case outcome
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(0 (mod (- opponent 1) 3))
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(1 opp)
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(2 (mod (+ 1 opponent) 3))
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(t 0)))
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(loop for round in rounds
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sum
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(destructuring-bind (opp you) round
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(let ((choice (get-correct-choice opp you)))
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(+ 1 choice
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(case you ;; outcome -> score
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(0 0)
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(1 3)
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(2 6)
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(t 0))))))
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