putting all my solutions together in 1 repository

3 files changed, 90 insertions, 0 deletions

diff --git a/2020/day-01/day-01.rkt b/2020/day-01/day-01.rkt
new file mode 100644
index 0000000..56c0b87
--- /dev/null
+++ b/2020/day-01/day-01.rkt
@@ -0,0 +1,23 @@
+#lang racket
+(require "../../jj-aoc.rkt"
+         threading)
+
+(define entries
+  (~>> (open-day 01 2020)
+       (port->list read)
+       list->set))
+
+;; part 1
+(define (look-for-complement xs)
+  (define x (set-first xs))
+  (cond
+    [(set-member? xs (- 2020 x)) (* x (- 2020 x))]
+    [else (look-for-complement (set-rest xs))]))
+
+(time (look-for-complement entries))
+
+;; part 2
+(time (for*/first ([x (in-set entries)]
+                   [y (in-set (set-subtract entries (set x)))]
+                   #:when (set-member? (set-subtract entries (set x y)) (- 2020 x y)))
+        (* x y (- 2020 x y))))
\ No newline at end of file
diff --git a/2020/day-02/day-02.rkt b/2020/day-02/day-02.rkt
new file mode 100644
index 0000000..3296d32
--- /dev/null
+++ b/2020/day-02/day-02.rkt
@@ -0,0 +1,45 @@
+#lang racket
+(require "../../jj-aoc.rkt"
+         threading)
+
+(struct policy (least most char pwd) #:transparent)
+
+(define (make-policy least-str most-str char-str pwd)
+  (policy (string->number least-str)
+          (string->number most-str)
+          (string-ref char-str 0)
+          pwd))
+
+(define policies
+  (for/list ([l (in-lines (open-day 02 2020))])
+    (~>> l
+         (regexp-match #px"(\\d+)-(\\d+) (\\w): (.*)")
+         rest
+         (apply make-policy))))
+
+;; part 1
+(define (valid-policy? p)
+  (~>> p
+       policy-pwd
+       string->list
+       (count (curry char=? (policy-char p)))
+       ((λ (n) (and (>= n (policy-least p))
+                    (<= n (policy-most p)))))))
+
+(for/sum ([p (in-list policies)]
+          #:when (valid-policy? p))
+  1)
+
+;; part 2
+(define (valid-revised-policy? p)
+  (~>> p
+       policy-pwd
+       string->list
+       ((λ (lst) (list (list-ref lst (sub1 (policy-most p)))
+                       (list-ref lst (sub1 (policy-least p))))))
+       (count (curry char=? (policy-char p)))
+       (= 1)))
+
+(for/sum ([p (in-list policies)]
+          #:when (valid-revised-policy? p))
+  1)
\ No newline at end of file
diff --git a/2020/day-03/day-03.rkt b/2020/day-03/day-03.rkt
new file mode 100644
index 0000000..f540ee6
--- /dev/null
+++ b/2020/day-03/day-03.rkt
@@ -0,0 +1,22 @@
+#lang racket
+(require "../../jj-aoc.rkt"
+         threading)
+
+(define (check-for-trees run rise)
+  (for*/sum ([(row i) (in-indexed (port->lines (open-day 3 2020)))]
+             #:when (= 0 (modulo i rise))
+             [possible-tree (in-value (sequence-ref (in-cycle row) (* (/ run rise) i)))]
+             #:when (and (char=? possible-tree #\#)))
+    1))
+
+;; part 1
+(check-for-trees 3 1)
+
+;; part 2
+(~>> '((1 1)
+       (3 1)
+       (5 1)
+       (7 1)
+       (1 2))
+     (map (curry apply check-for-trees))
+     (apply *))
\ No newline at end of file