diff options
Diffstat (limited to '11')
| -rw-r--r-- | 11/1.rkt | 2 | ||||
| -rw-r--r-- | 11/2.rkt | 87 |
2 files changed, 87 insertions, 2 deletions
@@ -55,8 +55,6 @@ (loop (+ 1 i) (+ 2 i) ret) (loop i (+ 1 j) (cons (cons i j) ret)))))) - - (define (distance n1 n2) (define x1 (car (vector-ref galaxies n1))) (define x2 (car (vector-ref galaxies n2))) diff --git a/11/2.rkt b/11/2.rkt new file mode 100644 index 0000000..a8f0e67 --- /dev/null +++ b/11/2.rkt @@ -0,0 +1,87 @@ +#lang racket + +(require "../lib/utils.rkt") + +(define lines + (call-with-input-file "input" + (λ (fp) (get-lines fp)))) + +(set! lines (list->vector lines)) + +(define (transpose linesvec) + (define lines (vector->list linesvec)) + (define width (string-length (vector-ref linesvec 0))) + (define new-lines (make-vector width)) + (let loop ((i 0)) + (if (>= i width) + new-lines + (let () + (define char-list (map (λ (l) (string-ref l i)) lines)) + (vector-set! new-lines i (list->string char-list)) + (loop (+ i 1)))))) + +(define (get-rows-to-expand lines) + (let loop ((i 0) (ret '())) + (if (>= i (vector-length lines)) + (reverse (cons 9999999 ret)) + (let () + (define str (vector-ref lines i)) + (if (andmap (λ (c) (char=? #\. c)) + (string->list str)) + (loop (+ 1 i) (cons i ret)) + (loop (+ 1 i) ret)))))) + +(define rows-to-expand (get-rows-to-expand lines)) +(define columns-to-expand (get-rows-to-expand (transpose lines))) + +(define height (vector-length lines)) +(define width (string-length (vector-ref lines 0))) + +(define expand-param 1000000) + +(define (build-expand-map num rows-to-expand) + (define map (make-vector num)) + (let loop ((i 0) (cur 0) (rows rows-to-expand)) + (if (>= i num) + map + (begin + (vector-set! map i cur) + (if (= i (car rows)) + (loop (+ 1 i) (+ expand-param cur) (cdr rows)) + (loop (+ 1 i) (+ 1 cur) rows)))))) + +(define row-expand-map (build-expand-map height rows-to-expand)) +(define column-expand-map (build-expand-map width columns-to-expand)) + +(define (get-galaxies universe) + (define (char-at x y) (string-ref (vector-ref universe y) x)) + (let loop ((x 0) (y 0) (ret '())) + (if (>= y height) + (list->vector (reverse ret)) + (if (>= x width) + (loop 0 (+ y 1) ret) + (if (char=? #\# (char-at x y)) + (loop (+ x 1) y (cons (cons x y) ret)) + (loop (+ x 1) y ret)))))) + +(define galaxies (get-galaxies lines)) + +(define (gen-pairs n) + (let loop ((i 0) (j 1) (ret '())) + (if (>= i n) + (reverse ret) + (if (>= j n) + (loop (+ 1 i) (+ 2 i) ret) + (loop i (+ 1 j) (cons (cons i j) ret)))))) + +(define (distance n1 n2) + (define x1 (vector-ref column-expand-map (car (vector-ref galaxies n1)))) + (define x2 (vector-ref column-expand-map (car (vector-ref galaxies n2)))) + (define y1 (vector-ref row-expand-map (cdr (vector-ref galaxies n1)))) + (define y2 (vector-ref row-expand-map (cdr (vector-ref galaxies n2)))) + (+ (abs (- x1 x2)) (abs (- y1 y2)))) + +(apply + + + (map (λ (x) (distance (car x) (cdr x))) + (gen-pairs (vector-length galaxies))))
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