1 files changed, 46 insertions, 0 deletions
diff --git a/2021/17/code.tl b/2021/17/code.tl
new file mode 100644
index 0000000..af76de0
--- /dev/null
+++ b/2021/17/code.tl
@@ -0,0 +1,46 @@
+(defstruct spec ()
+  x0 x1
+  y0 y1)
+
+(defun read-input (: (name "input"))
+  (flow name
+    file-get-string
+    (match `target area: x=@x0..@x1, y=@y0..@y1\n@nil` @1
+      (new spec x0 (toint x0) x1 (toint x1) y0 (toint y0) y1 (toint y1)))))
+
+(defun simulate-shot (sp xv yv)
+  (let ((x0 sp.x0) (x1 sp.x1)
+        (y0 sp.y0) (y1 sp.y1))
+  (for ((x 0) (y 0) (maxy -1000)) () ()
+    (cond
+      ((or (< y y0) (> x x1))
+       (return))
+      ((and (<= x0 x x1) (<= y0 y y1))
+       (return maxy)))
+    (inc x xv)
+    (inc y yv)
+    (upd maxy (max y maxy))
+    (dec xv (signum xv))
+    (dec yv 1))))
+
+(defun solve-one (: (name :))
+  (let ((sp (read-input name)))
+    (flow
+      (build
+        (each-prod ((xv 1..40)
+                    (yv 1..700))
+          (iflet ((maxy (simulate-shot sp xv yv)))
+            (add (list xv yv maxy)))))
+      (find-max @1 : caddr))))
+
+(defun solve-two (: (name :))
+  (let ((sp (read-input name)))
+    (flow
+      (build
+        (each-prod ((xv 1..300)
+                    (yv -100..400))
+          (iflet ((maxy (simulate-shot sp xv yv)))
+            (add (list xv yv maxy)))))
+      (mapcar (ap list @1 @2))
+      uniq
+      len)))