Add 2021 advent - day 1.

Time to learn Racket/Scheme?

2021/day1/day1.rkt

@@ -0,0 +1,16 @@
+#lang racket
+
+(define (go)
+  'yep-it-works)
+(go)
+
+(define count 0)
+(define old 5000)
+(for ([t (in-lines)])
+	  (define new (string->number t))
+	  (if (> new old)
+		 (set! count (+ count 1))
+		 #f)
+	  (set! old new))
+
+(display count)

2021/day1/day1p2.rkt

@@ -0,0 +1,23 @@
+#lang racket
+
+(define l null)
+(for ([t (in-lines)])
+	  (define new (string->number t))
+	  (set! l (cons new l)))
+
+(define v (list->vector (reverse l)))
+
+(define (vsum vec pos)
+  (define p1 (vector-ref vec pos))
+  (define p2 (vector-ref vec (+ pos 1)))
+  (define p3 (vector-ref vec (+ pos 2)))
+  (+ p1 (+ p2 p3)))
+
+(define count 0)
+(define len (vector-length v))
+(for/list ([i (in-range len)])
+			 (if (and (<= (+ i 4) len) (< (vsum v i) (vsum v (+ i 1))))
+				(set! count (+ count 1))
+				#f))
+
+(display count)

2021/day1/txt1

@@ -0,0 +1,10 @@
+199
+200
+208
+210
+200
+207
+240
+269
+260
+263