Question

我已经编写了这段代码，但是当我编写64时，它说不是完美的立方体，为什么？

num=int(input('num: '))


for i in range(0,num+1):

    if num==i**3:
        print('It is perfect cube')
    else:
        print('not perfect cube')
        break

Answer 1

如果您检查的num == i**3的每个值的i为假，则只想打印“不是完美的立方体”，而不仅仅是其中之一。基本上，您希望将else附加到for循环，而不是if语句，

for i in range(num+1):
    if num == i**3:
        print('It is a perfect cube')
        break  # Don't need to check more
else:
    # Only executed if the loop ends "naturally", not via a break
    print('It is not a perfect cube')

如果您想一次i ** 3 > num停止循环，这会变得更加复杂。您需要一个标志来表明您是由于发现多维数据集根而中断，还是因为您知道没有中断。一种可能的方法：

cube = False
for i in range(num+1):
    tmp = i ** 3
    if num == tmp:
        print('It is a perfect cube')
        cube = True
        break
    elif num < tmp:
        break
else:
    if not cube:
        print('Not a cube')

Answer 2

$ssl=new ssl();

$x="this was encrpyted";
echo "<br />1".$x;
$json=$ssl->encrypt($x);
echo "<br />2".$json;
echo "<br />3".$ssl->decrypt($json);

class ssl {

    private $cipher = "aes-128-gcm";
    private $options=0;

    public function encrypt($plaintext) {
        $key=openssl_random_pseudo_bytes(16);
        $ivlen=openssl_cipher_iv_length($this->cipher);
        $iv=openssl_random_pseudo_bytes($ivlen);
        $ciphertext=openssl_encrypt(
            $plaintext, 
            $this->cipher, 
            $key,
            $this->options,
            $iv,
            $tag
        );
        $a=[];
        $a["key"]=bin2hex($key);    
        $a["iv"]=bin2hex($iv);  
        $a["ciphertext"]=$ciphertext;   
        return json_encode($a);
    }

    public function decrypt($json) {
        $a=json_decode($json,true);
        return openssl_decrypt(
            $a["ciphertext"], 
            $this->cipher, 
            hex2bin($a["key"]),
            $this->options,
            hex2bin($a["iv"])
        );
    }

}

Answer 3

一种快速版本，找到解决方案后将停止评估值。

num = int(input('num: '))
if any(num == i ** 3 for i in range(num)):
    print('perfect cube')
else:
    print('not perfect cube')

找到完美立方体的Python程序

3 个答案: