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- (import (chicken string))
- (import (chicken io))
- (import (chicken sort))
- (import matchable)
- (import srfi-1)
- (import regex)
- (define input
- (with-input-from-file "input"
- (lambda ()
- (let loop ((ret '()))
- (let ((line (read-line)))
- (if (eof-object? line)
- (reverse ret)
- (loop (cons line ret))))))))
- (define (transpose in)
- (define cols (string-length (car in)))
- (let loop ((i 0) (ret '()))
- (if (>= i cols)
- (reverse ret)
- (loop (+ i 1) (cons (list->string (map (lambda (x) (string-ref x i))
- in))
- ret)))))
- (define (flip in)
- (define (flip-row row)
- (list->string (reverse (string->list row))))
- (map flip-row in))
- (define (char-at in x y)
- (string-ref (list-ref in y) x))
- (define (diag in)
- (define width (string-length (car in)))
- (define height (length in))
- (define (diag-start-at x y)
- (let loop ((cur-row y) (cur-col x) (ret '()))
- (if (or (< cur-col 0)
- (>= cur-row height))
- (list->string (reverse ret))
- (loop (+ cur-row 1)
- (- cur-col 1)
- (cons (char-at in cur-col cur-row) ret)))))
- (define (row-diag in)
- (let loop ((i 0) (ret '()))
- (if (>= i width)
- (reverse ret)
- (loop (+ 1 i) (cons (diag-start-at i 0) ret)))))
- (define (col-diag in)
- (let loop ((i 1) (ret '()))
- (if (>= i height)
- (reverse ret)
- (loop (+ i 1) (cons (diag-start-at (- width 1) i) ret)))))
- (append (row-diag in) (col-diag in)))
- (define (count-xmas str)
- (define len (string-length str))
- (let loop ((cur 0) (count 0))
- (define pos (string-search-positions "XMAS" str cur))
- (if pos
- (loop (cadar pos) (+ 1 count))
- count)))
- (define (count-mat mat)
- (apply + (map count-xmas mat)))
- (define mat-list
- (list input (flip input)
- (transpose input) (flip (transpose input))
- (diag input) (flip (diag input))
- (diag (flip input)) (flip (diag (flip input)))))
- (display (apply + (map count-mat mat-list)))
- (newline)
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