4 files changed, 147 insertions, 0 deletions
diff --git a/2021/12/input b/2021/12/input
new file mode 100644
index 0000000..756681b
--- /dev/null
+++ b/2021/12/input
@@ -0,0 +1,23 @@
+pn-TY
+rp-ka
+az-aw
+al-IV
+pn-co
+end-rp
+aw-TY
+rp-pn
+al-rp
+end-al
+IV-co
+end-TM
+co-TY
+TY-ka
+aw-pn
+aw-IV
+pn-IV
+IV-ka
+TM-rp
+aw-PD
+start-IV
+start-co
+start-pn
diff --git a/2021/12/one.tl b/2021/12/one.tl
new file mode 100644
index 0000000..70e36d5
--- /dev/null
+++ b/2021/12/one.tl
@@ -0,0 +1,49 @@
+(defvar %cave-hash% (hash))
+
+(defstruct cave ()
+  name
+  neighbors
+
+  (:postinit (cv)
+    (assert cv.name)
+    (set [%cave-hash% cv.name] cv)))
+
+(defstruct small-cave cave
+  (:method visit (cv path fn)
+    (unless (member cv path)
+      (push cv path)
+      (each ((n cv.neighbors))
+        n.(visit path fn)))))
+
+(defstruct big-cave cave
+  (:method visit (cv path fn)
+    (push cv path)
+    (each ((n cv.neighbors))
+      n.(visit path fn))))
+
+(defstruct end-cave cave
+  (:method visit (cv path fn)
+    (push cv path)
+    [fn path]))
+
+(defun ensure-cave (name)
+  (or [%cave-hash% name]
+      (set [%cave-hash% name]
+           (match-case name
+             ("end" (new end-cave name name))
+             (@[all @str chr-islower] (new small-cave name name))
+             (@else (new big-cave name name))))))
+
+(defun read-caves (: (name "input"))
+  (with-stream (s (open-file name))
+    (whilet ((line (get-line s)))
+      (match `@a-@b` line
+        (let ((ca (ensure-cave a))
+              (cb (ensure-cave b)))
+          (pushnew cb ca.neighbors)
+          (pushnew ca cb.neighbors))))))
+
+(defun find-paths (fn)
+  (let ((start [%cave-hash% "start"]))
+    (assert start)
+    start.(visit nil fn)))
diff --git a/2021/12/testinput b/2021/12/testinput
new file mode 100644
index 0000000..6fd8c41
--- /dev/null
+++ b/2021/12/testinput
@@ -0,0 +1,7 @@
+start-A
+start-b
+A-c
+A-b
+b-d
+A-end
+b-end
diff --git a/2021/12/two.tl b/2021/12/two.tl
new file mode 100644
index 0000000..69f179a
--- /dev/null
+++ b/2021/12/two.tl
@@ -0,0 +1,68 @@
+(defvar %cave-hash% (hash))
+
+(defstruct cave ()
+  name
+  neighbors
+
+  (:postinit (cv)
+    (assert cv.name)
+    (set [%cave-hash% cv.name] cv)))
+
+(defstruct end-cave cave
+  (:method visit (cv path fn)
+    (push cv path)
+    [fn (remq t path)]))
+
+(defstruct start-cave cave
+  (:method visit (cv path fn)
+    (unless (member cv path)
+      (push cv path)
+      (each ((n cv.neighbors))
+        n.(visit path fn)))))
+
+(defstruct small-cave cave
+  (:method visit (cv path fn)
+    (let ((in-path (member cv path)))
+      (when (or (not in-path)
+                (not (member t path)))
+        (push cv path)
+        (if in-path
+          (push t path))
+        (each ((n cv.neighbors))
+          n.(visit path fn))))))
+
+(defstruct big-cave cave
+  (:method visit (cv path fn)
+    (push cv path)
+    (each ((n cv.neighbors))
+      n.(visit path fn))))
+
+(defun ensure-cave (name)
+  (or [%cave-hash% name]
+      (set [%cave-hash% name]
+           (match-case name
+             ("end" (new end-cave name name))
+             ("start" (new start-cave name name))
+             (@[all @str chr-islower] (new small-cave name name))
+             (@else (new big-cave name name))))))
+
+(defun read-caves (: (name "input"))
+  (with-stream (s (open-file name))
+    (whilet ((line (get-line s)))
+      (match `@a-@b` line
+        (let ((ca (ensure-cave a))
+              (cb (ensure-cave b)))
+          (pushnew cb ca.neighbors)
+          (pushnew ca cb.neighbors))))))
+
+(defun find-paths (fn)
+  (let ((start [%cave-hash% "start"]))
+    (assert start)
+    start.(visit nil fn)))
+
+(defun solve (: (name "input"))
+  (let (paths)
+    (read-caves name)
+    (find-paths (opip reverse (mapcar .name) (push @1 paths)))
+    (mapdo [chain (ap join-with ",") pprinl] paths)
+    (len paths)))