From 5b1a9f0e4ee23d1a522ac55ad6b7200b09e937cc Mon Sep 17 00:00:00 2001
From: Sidney Zhang <zly@lyzhang.me>
Date: Wed, 7 Jan 2026 18:33:01 +0800
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20feat(euler=5F37.py)=EF=BC=9A?=
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---
 solutions/0037.TruncatablePrimes/euler_37.py | 52 ++++++++++++++++++--
 1 file changed, 48 insertions(+), 4 deletions(-)

diff --git a/solutions/0037.TruncatablePrimes/euler_37.py b/solutions/0037.TruncatablePrimes/euler_37.py
index 377e9c2..c5799c2 100644
--- a/solutions/0037.TruncatablePrimes/euler_37.py
+++ b/solutions/0037.TruncatablePrimes/euler_37.py
@@ -9,10 +9,22 @@ Find the sum of the only eleven primes that are both truncatable from left to ri
 NOTE: 2, 3, 5, and 7 are not considered to be truncatable primes.
 """
 
+import time
 from itertools import product
 
 
-def combine_lists(a: list[int], b: list[int|None], c: list[int]) -> list[int]:
+def timer(func):
+    def wrapper(*args, **kwargs):
+        start_time = time.time()
+        result = func(*args, **kwargs)
+        end_time = time.time()
+        print(f"Time taken: {end_time - start_time:.6f} seconds")
+        return result
+
+    return wrapper
+
+
+def combine_lists(a: list[int], b: list[int | None], c: list[int]) -> list[int]:
     """将三个列表的每个元素组合成数字"""
     return [int(f"{x}{y}{z}") for x, y, z in product(a, b, c)]
 
@@ -21,12 +33,32 @@ def is_prime(n: int) -> bool:
     """判断一个数是否为素数"""
     if n < 2:
         return False
-    for i in range(2, int(n ** 0.5) + 1):
+    for i in range(2, int(n**0.5) + 1):
         if n % i == 0:
             return False
     return True
 
 
+def truncate_left(n: int) -> bool:
+    """从左到右截断一个数"""
+    length = len(str(n))
+    while n > 0:
+        if not is_prime(n):
+            return False
+        n %= 10 ** (length - 1)
+        length -= 1
+    return True
+
+
+def truncate_right(n: int) -> bool:
+    """从右到左截断一个数"""
+    while n > 0:
+        if not is_prime(n):
+            return False
+        n //= 10
+    return True
+
+
 def TruncatablePrime() -> list[int]:
     begin = [2, 3, 5, 7]
     end = [3, 7]
@@ -39,5 +71,17 @@ def TruncatablePrime() -> list[int]:
             midb = product(middle, repeat=length - 2)
             midb = [int("".join(map(str, x))) for x in midb]
         nums = combine_lists(begin, midb, end)
-        for num in nums :
-            if is
+        for num in nums:
+            if is_prime(num):
+                if truncate_left(num) and truncate_right(num):
+                    res.append(num)
+    return res
+
+
+@timer
+def main():
+    print(sum(TruncatablePrime()))
+
+
+if __name__ == "__main__":
+    main()