diff --git a/2024/day21/challenge b/2024/day21/challenge
new file mode 100644
index 0000000..e69de29
diff --git a/2024/day21/code.py b/2024/day21/code.py
new file mode 100755
index 0000000..06a10d9
--- /dev/null
+++ b/2024/day21/code.py
@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+
+import sys, math
+from itertools import permutations, product
+
+#     +---+---+
+#     | ^ | A |
+# +---+---+---+
+# | < | v | > |
+# +---+---+---+
+DIR = {
+    'A': (0,2),
+    '^': (0,1),
+    '<': (-1,0),
+    'v': (-1,1),
+    '>': (-1,2),
+        }
+
+# +---+---+---+
+# | 7 | 8 | 9 |
+# +---+---+---+
+# | 4 | 5 | 6 |
+# +---+---+---+
+# | 1 | 2 | 3 |
+# +---+---+---+
+#     | 0 | A |
+#     +---+---+
+NUM = {
+#         ('A', '0'): ['<'],
+#         ('A', '1'): ['<^<', '^<<'],
+#         ('A', '2'): ['<^', '^<'],
+#         ('A', '3'): ['^'],
+#         ('A', '4'): ['<^<^', '^<<^', '^^<<', '<^^<'],
+#         ('A', '5'): ['<^^', '^<^', '^^<'],
+#         ('A', '6'): ['^^'],
+#         ('A', '7'): ['^^^<<', '^^<<^', '^<<^^', '^<^<^', '^<^^<'],
+#         ('A', '8'): ['<^^', '^<^', '^^<'],
+#         ('A', '9'): ['^^^',],
+    'A': (0,2),
+    '0': (0,1),
+    '1': (1,0),
+    '2': (1,1),
+    '3': (1,2),
+    '4': (2,0),
+    '5': (2,1),
+    '6': (2,2),
+    '7': (3,0),
+    '8': (3,1),
+    '9': (3,2),
+        }
+
+
+def options(start,end, pad):
+    s, e = pad[start], pad[end]
+    d = {'^': (1,0), 'v': (-1,0), '>': (0,1), '<': (0,-1)}
+    dy = e[0]-s[0]
+    dx = e[1]-s[1]
+    opt = ['^'] * dy + ['v'] * -dy + ['<'] * -dx + ['>'] * dx
+    for o in set(permutations(opt)):
+        s, e = pad[start], pad[end]
+        gap = False
+        for step in list(o):
+            s = s[0] + d[step][0], s[1] + d[step][1]
+            if s == (0,0): gap = True
+        if not gap: yield ''.join(o+('A',))
+
+
+def directional(code):
+    strings = ['']
+    prev = 'A'
+    for key in list(code):
+        strings = [s1+s2 for (s1,s2) in product(strings,[opt for opt in options(prev, key, DIR)])]
+        prev = key
+    return strings
+
+
+def numeric(code):
+    strings = ['']
+    prev = 'A'
+    for key in list(code):
+        strings = [s1+s2 for (s1,s2) in product(strings,[opt for opt in options(prev, key, NUM)])]
+        prev = key
+    return strings
+
+
+if __name__ == '__main__':
+    codes = [line.strip('\n') for line in open(sys.argv[1])]
+    res1 = 0
+    for code in codes:
+        length = math.inf
+        opts = []
+        for dirs in sorted(numeric(code),key=len):
+            for dirs1 in set(directional(dirs)):
+                for dirs2 in set(directional(dirs1)):
+                    if len(dirs2) <= length:
+                        opts.append(dirs2)
+                        length = len(dirs2)
+                    else: break
+                    
+        res1 += length * int(code[:-1])
+                    
+    # challenge 1
+    print(f"challenge 1:\n{res1}\n")
+
+    # challenge 2
+    res2 = ""
+    print(f"challenge 2:\n{res2}")
+
diff --git a/2024/day21/example b/2024/day21/example
new file mode 100644
index 0000000..4cf0c29
--- /dev/null
+++ b/2024/day21/example
@@ -0,0 +1,5 @@
+029A
+980A
+179A
+456A
+379A
diff --git a/2024/day21/input b/2024/day21/input
new file mode 100644
index 0000000..fc1d950
--- /dev/null
+++ b/2024/day21/input
@@ -0,0 +1,5 @@
+985A
+540A
+463A
+671A
+382A