init

1 files changed, 112 insertions, 0 deletions

diff --git a/advent-of-code/2023/05/part2.scm b/advent-of-code/2023/05/part2.scm
new file mode 100755
index 0000000..87ad5e9
--- /dev/null
+++ b/advent-of-code/2023/05/part2.scm
@@ -0,0 +1,112 @@
+#!/usr/bin/env guile
+!#
+
+(use-modules (ice-9 rdelim))
+
+(define port (open-input-file "input"))
+
+(define seed 
+  (let ()
+    (define nums-str 
+      (string-trim
+          (list-ref (string-split (read-line port) #\:) 1)))
+    (define (pairing l)
+      (define (loop ret l)
+        (if (null? l)
+          ret
+          (loop
+            (cons (cons 
+                    (car l) 
+                    (+ (car l) (cadr l)))
+                  ret)
+            (cddr l))))
+      (loop '() l))
+    (reverse 
+      (pairing (map string->number (string-split nums-str #\space))))))
+
+(read-line port)
+
+(define (read-line-convert-eof port)
+  (define line (read-line port))
+  (if (eof-object? line) "" line))
+
+(define (read-map)
+  (define (loop ret)
+    (define line (string-trim (read-line-convert-eof port)))
+    (if (= 0 (string-length line))
+      (sort (reverse ret) (lambda (x y) (< (cadr x) (cadr y))))
+      (loop (cons (map string->number (string-split line #\space))
+                  ret))))
+  (read-line port)
+  (loop '()))
+
+(define s2s (read-map))
+(define s2f (read-map))
+(define f2w (read-map))
+(define w2l (read-map))
+(define l2t (read-map))
+(define t2h (read-map))
+(define h2l (read-map))
+(define maps (list s2s s2f f2w w2l l2t t2h h2l))
+
+(define (range-map mlist r)
+  ;; r :: Range :: (start . end)
+  ;; mlist :: List of (Map :: (dest, src, len))
+  (define (loop result mlist r)
+    (define start (car r))
+    (define end (cdr r))
+    (if (null? mlist)
+      (cons r result)
+      (let ()
+        (define cur-map (car mlist))
+        (define map-target (car cur-map))
+        (define map-start (cadr cur-map))
+        (define map-end (+ map-start (caddr cur-map)))
+        (define offset (- map-target map-start))
+        (define (pair-offset p) (cons (+ offset (car p)) (+ offset (cdr p))))
+        (cond ((<= end start)
+                    result)
+              ((>= start map-end)
+                    (loop result (cdr mlist) r))
+              ((>= start map-start)
+                    (loop
+                      (cons (pair-offset (cons start (min end map-end)))
+                            result)
+                      (cdr mlist)
+                      (cons (min end map-end) end)))
+              ((<= end map-start)
+                    (cons r result))
+              ((< start map-start)
+                    (loop
+                      (cons (cons start map-start) result)
+                      mlist
+                      (cons map-start end)))
+              (else (error "unhandled cond in range-map"))))))
+  (reverse (loop '() mlist r)))
+
+(define (gen-range-mapper the-map)
+  (define (mapper range-list)
+    (apply append
+        (map 
+            (lambda (range)
+              (range-map the-map range)) 
+            range-list)))
+  mapper)
+
+(define mappers (map gen-range-mapper maps))
+
+(define (comp-func funcs)
+  (define procs (reverse funcs))
+  (define (comp-rec arg)
+    (if (null? procs)
+        arg
+        (let ((proc (car procs))
+              (rest (cdr procs)))
+          (set! procs rest)
+          (proc (comp-rec arg)))))
+  comp-rec)
+
+(define (find-location x)
+  ((comp-func mappers) x))
+
+(display (apply min (map car (find-location seed))))