day 18: now concise-er

1 files changed, 8 insertions, 9 deletions

diff --git a/18.py b/18.py
index 4281c57..f1b1b86 100644
--- a/18.py
+++ b/18.py
@@ -41,15 +41,14 @@ def try_explode(n, depth=0):
         return val
     if not is_pair(n): return None
     if depth == 4: return n
-    car_val = try_explode(n.car, depth + 1)
-    if car_val is not None:
-        if depth == 3: n.car = 0
-        return Pair(car_val.car, try_add(n, car_val.cdr, cdr, car, cdr))
-    else:
-        cdr_val = try_explode(n.cdr, depth + 1)
-        if cdr_val is not None:
-            if depth == 3: n.cdr = 0
-            return Pair(try_add(n, cdr_val.car, car, cdr, car), cdr_val.cdr)
+    for access in (car, cdr):
+        val = try_explode(access(n), depth + 1)
+        if val is None: continue
+        if depth == 3: access(n, 0)
+        if access == car:
+            return Pair(val.car, try_add(n, val.cdr, cdr, car, cdr))
+        else:
+            return Pair(try_add(n, val.car, car, cdr, car), val.cdr)
 
 tests = [
     ('[[[[[9,8],1],2],3],4]', '[[[[0,9],2],3],4]'),