e = '| * |'.join(f)
时间: 2023-12-28 22:25:23 浏览: 40
e = '| * |'.join(f)是将列表f中的元素用'| * |'连接起来的操作。
示例代码如下:
```python
f = ['apple', 'banana', 'orange']
e = '| * |'.join(f)
print(e) # 输出:apple| * |banana| * |orange
```
相关问题:
1. 如何将字符串按照指定分隔符连接起来?
2. 如何将列表中的元素用特定字符连接起来?
3. 如何将字典中的值用特定字符连接起来?
相关问题
优化这个语句 SELECT d.*, f.create_time as submit_time, e.name as name FROM `order` d, verify_process f, user e where d.id = f.`order_id` and e.id = d.user_id AND f.`is_complete` = 0 and d.`delete_flag` = 0 and (f.`next_verify_role_id` IN <foreach collection="roleIds" item="item" index="index" separator=" , " open="(" close=")"> #{item} </foreach> )
这个语句可以进行以下优化:
1. 使用 JOIN 代替多张表的 FROM 关联,这样能够提高查询效率,并且更易于理解和维护。
2. 添加索引来优化 WHERE 子句中的查询条件,例如 `order_id`、`user_id`、`is_complete` 和 `delete_flag` 等字段可以添加索引。
3. 如果 `roleIds` 集合比较大,可以考虑将其转换为临时表或者使用其他方法进行优化。
优化后的语句如下:
```
SELECT d.*, f.create_time as submit_time, e.name as name
FROM `order` d
JOIN verify_process f ON d.id = f.`order_id`
JOIN user e ON e.id = d.user_id
WHERE f.`is_complete` = 0
AND d.`delete_flag` = 0
AND f.`next_verify_role_id` IN (
SELECT item FROM (
SELECT DISTINCT item FROM (
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(t.`roleIds`, ',', n.n), ',', -1) item
FROM (
SELECT #{roleIds} AS `roleIds`
) t
JOIN (
SELECT @rownum:=@rownum+1 AS n FROM (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3) a, (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3) b, (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3) c, (SELECT @rownum:=0) r
) n
ON CHAR_LENGTH(t.`roleIds`) - CHAR_LENGTH(REPLACE(t.`roleIds`, ',', '')) >= n.n - 1
) tmp
) tmp2
)
```
其中,`roleIds` 是传入的参数,表示需要查询的 `next_verify_role_id` 值的集合。这里使用了 MySQL 中的 `SUBSTRING_INDEX` 和 `JOIN` 函数来实现将 `roleIds` 字符串转换为临时表,并且使用了 `DISTINCT` 关键字去重。
修改代码from Crypto.Util.number import * from Crypto.PublicKey import RSA from hashlib import sha256 import random, os, signal, string def proof_of_work(): random.seed(os.urandom(8)) proof = ''.join([random.choice(string.ascii_letters+string.digits) for _ in range(20)]) _hexdigest = sha256(proof.encode()).hexdigest() print(f"sha256(XXXX+{proof[4:]}) == {_hexdigest}") print('Give me XXXX: ') x = input() if len(x) != 4 or sha256(x.encode()+proof[4:].encode()).hexdigest() != _hexdigest: print('Wrong PoW') return False return True if not proof_of_work(): exit(1) signal.alarm(10) print("Give me a bad RSA keypair.") try: p = int(input('p = ')) q = int(input('q = ')) assert p > 0 assert q > 0 assert p != q assert p.bit_length() == 512 assert q.bit_length() == 512 assert isPrime(p) assert isPrime(q) n = p * q e = 65537 assert p % e != 1 assert q % e != 1 d = inverse(e, (p-1)*(q-1)) except: print("Invalid params") exit(2) try: key = RSA.construct([n,e,d,p,q]) print("This is not a bad RSA keypair.") exit(3) except KeyboardInterrupt: print("Hacker detected.") exit(4) except ValueError: print("How could this happen?") from secret import flag print(flag)
为了修复这个程序的漏洞,可以加入一个时间限制,如果用户输入的参数过大导致程序运行时间过长,程序会自动退出。代码如下所示:
```python
from Crypto.Util.number import *
from Crypto.PublicKey import RSA
from hashlib import sha256
import random, os, signal, string
def proof_of_work():
random.seed(os.urandom(8))
proof = ''.join([random.choice(string.ascii_letters+string.digits) for _ in range(20)])
_hexdigest = sha256(proof.encode()).hexdigest()
print(f"sha256(XXXX+{proof[4:]}) == {_hexdigest}")
print('Give me XXXX: ')
x = input()
if len(x) != 4 or sha256(x.encode()+proof[4:].encode()).hexdigest() != _hexdigest:
print('Wrong PoW')
return False
return True
if not proof_of_work():
exit(1)
signal.alarm(10)
print("Give me a bad RSA keypair.")
try:
p = int(input('p = '))
q = int(input('q = '))
assert p > 0
assert q > 0
assert p != q
assert p.bit_length() == 512
assert q.bit_length() == 512
assert isPrime(p)
assert isPrime(q)
n = p * q
e = 65537
assert p % e != 1
assert q % e != 1
d = inverse(e, (p-1)*(q-1))
key = RSA.construct([n,e,d,p,q])
print("This is not a bad RSA keypair.")
exit(3)
except AssertionError:
print("Invalid params")
exit(2)
except KeyboardInterrupt:
print("Time limit exceeded")
exit(4)
except ValueError:
print("How could this happen?")
from secret import flag
print(flag)
```
在新代码中,我们使用了 signal 库中的 alarm 函数,将程序的运行时间限制在 10 秒钟内。当用户输入的参数过大导致程序运行时间超过 10 秒时,程序会自动退出,并输出 "Time limit exceeded"。
相关推荐
![pdf](https://img-home.csdnimg.cn/images/20210720083512.png)
![js](https://img-home.csdnimg.cn/images/20210720083646.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)