diff --git a/aoc.asd b/aoc.asd
index 831d582..f1d17ea 100644
--- a/aoc.asd
+++ b/aoc.asd
@@ -34,6 +34,7 @@
 		 (:file "2024/day07")
 		 (:file "2024/day08")
 		 (:file "2024/day09")
+		 (:file "2024/day10")
 		 )))
   :description "Advent of Code challenges and solutions."
   :long-description "Solutions for the AOC challenges."
@@ -59,6 +60,7 @@
 		 (:file "2024/day07-test")
 		 (:file "2024/day08-test")
 		 (:file "2024/day09-test")
+		 (:file "2024/day10-test")
 		 )))
   :description "Test system for aoc"
   :perform (test-op (op c) (symbol-call :parachute :test :aoc/tests)))
diff --git a/src/2024/day10.lisp b/src/2024/day10.lisp
new file mode 100644
index 0000000..b9dfcdd
--- /dev/null
+++ b/src/2024/day10.lisp
@@ -0,0 +1,155 @@
+(defpackage :aoc/2024/10
+	    (:use :cl :aoc :alexandria :trivia :lla)
+	    (:export
+	     #:sample-data
+	     #:sample-data2
+	     #:part1
+	     #:part2
+	     ))
+
+(in-package :aoc/2024/10)
+
+
+(defun parse-line (line)
+  (map 'vector (lambda (c) (or (digit-char-p c) 0)) (coerce line 'list)))
+
+
+(defun parse-input (lines)
+  (let ((heights (mapcar #'parse-line lines)))
+    (make-array `(,(length (first heights)) ,(length heights)) :initial-contents heights))
+  )
+
+(defparameter input-text (test-input 2024 10))
+(defparameter input-data (parse-input input-text))
+
+(defparameter sample-text (aoc:split-lines  "89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732"))
+(defparameter sample-data 
+  (parse-input sample-text))
+
+(defparameter sample-data-0 (parse-input (aoc:split-lines "...0...
+...1...
+...2...
+6543456
+7.....7
+8.....8
+9.....9")))
+
+(defparameter sample-data-1 (parse-input (aoc:split-lines "..90..9
+...1.98
+...2..7
+6543456
+765.987
+876....
+987....")))
+
+(defun find-heights(h map)
+  (loop
+    for y from 0 below (array-dimension map 1) 
+    append
+    (loop
+      for x from 0 below (array-dimension map 1)
+      if (= h (aref map x y))
+	collect (cons x y))))
+
+(defun find-trailheads (map)
+  (find-heights 1 map))
+
+(defun find-trailends (map)
+  (find-heights 9 map))
+
+(defun get-xy (map x y)
+  (if (array-in-bounds-p map x y)
+      (aref map x y)
+      0))
+
+
+
+
+(defun surrounding-paths (trails x y)
+  (remove-duplicates
+   (append
+    (gethash (cons (1+ x) y) trails)
+    (gethash (cons (1- x) y) trails)
+    (gethash (cons x (1+ y)) trails)
+    (gethash (cons x (1- y)) trails)
+    )))
+
+(defun trails-update (trails map h)
+  (let ((nt (make-hash-table :test #'equal :size 100)))
+    (loop
+      for pt in (find-heights h map)
+      do (setf
+	  (gethash pt nt)
+	  (if (= h 9)
+	      (list pt)
+	      (surrounding-paths trails (car pt) (cdr pt))))
+      )
+    nt))
+
+(defun map-endpoints (map)
+  (let ((ep-map (make-hash-table :test #'equal)))
+    (loop
+      for h from 9 downto 0 
+      do (setf ep-map (trails-update ep-map map h)))
+    ep-map))
+
+(defun score (map)
+  (loop
+    for v being the hash-values in (map-endpoints map)
+    sum (length v)))
+
+
+(defun sum-surrounding (map x y)
+  (+
+   (get-xy map (1+ x) y)
+   (get-xy map (1- x) y)
+   (get-xy map x (1+ y))
+   (get-xy map x (1- y))
+   )
+  )
+
+(defun ratings-update (ratings map h)
+  (let ((nr (make-array (array-dimensions ratings) :initial-element 0)))
+    (loop
+      for pt in (find-heights h map)
+      do
+	 (let ((x (car pt))
+	       (y (cdr pt)))
+	   (setf (aref nr x y) (if (= h 9) 1 (sum-surrounding ratings x y))))
+
+      )
+    nr))
+
+(defun ratings (map)
+  (let ((ratings (make-array (array-dimensions map) :initial-element 0)))
+    (loop
+      for h from 9 downto 0
+      do (setf ratings (ratings-update ratings map h)))
+    ratings))
+
+(defun rating (map)
+  (loop for r across (aops:flatten (ratings map)) sum r)
+  )
+
+(defun part1 (data)
+  (format nil "~A" (score data)))
+
+(defun part2 (data)
+  (format nil "~A" (rating data)))
+
+(defun solve-day ()
+  (format t "part1: ~A~%" (part1 input-data))
+  (format t "part2: ~A~%" (part2 input-data)))
+
+(defun submit ()
+  (let ((p1 (part1 input-data))
+        (p2 (part2 input-data)))
+    (if p1 (submit-part1 2024 10 p1))
+    (if p2 (submit-part2 2024 10 p2))))
diff --git a/tests/2024/day10-test.lisp b/tests/2024/day10-test.lisp
new file mode 100644
index 0000000..939051a
--- /dev/null
+++ b/tests/2024/day10-test.lisp
@@ -0,0 +1,16 @@
+(defpackage :aoc/2024/10/tests
+            (:use :cl :aoc :aoc/tests :aoc/2024/tests :parachute :aoc/2024/10))
+
+(in-package :aoc/2024/10/tests)
+
+(define-test suite-2024-10
+                                        ;:parent suite-2024
+  )
+
+(define-test+run test-part1
+  :parent suite-2024-10
+  (is equal "36" (part1 sample-data)))
+
+(define-test+run test-part2
+  :parent suite-2024-10
+  (is equal "81" (part2 sample-data)))