diff --git a/py/aoc2024/day20.py b/py/aoc2024/day20.py
index 72c1b9db..426c0814 100644
--- a/py/aoc2024/day20.py
+++ b/py/aoc2024/day20.py
@@ -2,9 +2,7 @@
 Day 20: Race Condition
 """
 
-from functools import partial
-from itertools import takewhile
-from operator import gt
+from aoc2024.day20c import solve as _solve
 
 SAMPLE_INPUT = """
 ###############
@@ -42,17 +40,6 @@ def _getpath(data: str) -> list[tuple[tuple[int, int], int]]:
                 stack.append(((y, x), path | {(y, x): len(path)}))
 
 
-def _solve(path: list[tuple[tuple[int, int], int]], cheats: int, time: int) -> int:
-    return sum(
-        (distance := abs(y2 - y1) + abs(x2 - x1)) <= cheats
-        and distance + time <= abs(t2 - t1)
-        for i, ((y1, x1), t1) in enumerate(path)
-        for (y2, x2), t2 in takewhile(
-            partial(gt, ((y1 + cheats, x1 + 1),)), path[i + 1 :]
-        )
-    )
-
-
 def part1(data: str, time: int = 100) -> int:
     """
     >>> counts = [part1(SAMPLE_INPUT, time) for time in (2, 4, 6, 8, 10, 12, 20, 36, 38, 40, 64)]
diff --git a/py/aoc2024/day20c.py b/py/aoc2024/day20c.py
new file mode 100644
index 00000000..33b6e75b
--- /dev/null
+++ b/py/aoc2024/day20c.py
@@ -0,0 +1,29 @@
+# cython: boundscheck=False, wraparound=False, initializedcheck=False, embedsignature=True
+import cython
+from collections.abc import Sequence
+
+
+@cython.ccall
+def solve(
+    path: Sequence[tuple[tuple[int, int], int]], cheats: cython.int, time: cython.int
+) -> cython.int:
+    count: cython.int = len(path)
+    i: cython.int
+    result: cython.int = 0
+    for i in range(count):
+        y1: cython.int
+        x1: cython.int
+        t1: cython.int
+        (y1, x1), t1 = path[i]
+        j: cython.int
+        for j in range(i + 1, count):
+            y2: cython.int
+            x2: cython.int
+            t2: cython.int
+            (y2, x2), t2 = path[j]
+            if y2 > y1 + cheats or y2 == y1 + cheats and x2 > x1:
+                break
+            distance: cython.int = abs(y2 - y1) + abs(x2 - x1)
+            if distance <= cheats and distance + time <= abs(t2 - t1):
+                result += 1
+    return result
diff --git a/py/aoc2024/day22c.py b/py/aoc2024/day22c.py
index a2e04ac2..9aeb1878 100644
--- a/py/aoc2024/day22c.py
+++ b/py/aoc2024/day22c.py
@@ -1,9 +1,5 @@
 # cython: boundscheck=False, wraparound=False, initializedcheck=False, embedsignature=True
 # ruff: noqa: F821
-"""
-Day 22: Monkey Market
-"""
-
 import cython
 from cython.parallel import prange
 from cython.cimports.libc.string import memset