列表的数字相乘 python

Question

我有 3 位质数数组：

for num in range(100, 1000):
     if num > 1:
         for i in range(2, num):
             if (num % i) == 0:
                 break
             else:
             numere_prime.append(num)

列表是：

numere_prime = [[101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163...]

我需要的是将一个数字的每个数字相乘（例如 101 = 1 * 0 * 1），然后它显示所有 numere_prime 相乘后等于用户输入。到目前为止我做了什么：

    for elem in numere_prime:
        digits = [int(x) for x in str(elem)] # split digits into [1,0,1][1,0,3]...
        for n in list(digits):
            // n * n_at_next_index * n_at_next_index
            if //result of multiplying == //number set by input:
            //append digits to result list

结果应该是这样的：input (9) = [191, 313, 331, 911]

Answer 1

你的素数算法是错误的。您不能仅在任何因素失败时追加到列表中，您必须知道所有因素都失败了。而且您不必一直搜索到 num；您只需向上搜索 sqrt(num)。由于最大值是 1000，您可以在 33 处停止。此外，检查 num > 1 是愚蠢的，因为您从 100 开始范围。而且您不必将 digits 转换为列表；它已经是一个列表。

您可以通过在 get_primes 中使用 any 函数并在 filter_primes 中使用 yield 来缩短它的长度。稍后你会得到它。

def get_primes():
    numere_prime = []
    for num in range(100, 1000):
        prime = True
        for i in range(2, 34):
           if (num % i) == 0:
              prime = False
              break
        if prime:
           numere_prime.append(num)
    return numere_prime

def filter_primes(primes, magic):
    res = []
    for elem in primes:
        digits = [int(x) for x in str(elem)] 
        product = 1
        for n in digits:
            product *= n
        if product == magic:
            res.append(elem)
    return res

numere_prime = get_primes()

inp = int(input("Your value: "))

result = filter_primes(numere_prime, inp)
print(result)

Answer 2

primes = [101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163]
a = int(input('enter a nmber :'))
primes_useful = []
for i in primes :
    product = 1
    for k in str(i):
        product *= int(k)
    if product == a :
        primes_useful.append(i)

print(primes_useful)

Answer 3

numere_prime = []
for num in range(100, 1000):
    prime = True
    for i in range(2, num):
        if (num % i) == 0:
            prime = False
    if prime:
        numere_prime.append(num)


def prime_digit_prod(x):
    output = []
    for elem in numere_prime:
        digits = [int(x) for x in str(elem)] # split digits into [1,0,1][1,0,3]...
        result = 1
        for n in digits:
            result *= n
        if result == x:
            output.append(elem)
    return output

print(prime_digit_prod(9))

输出：

[191, 313, 331, 911]

Answer 4

numere_prime = [101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157]
digi_mult_dict = {}
for elem in numere_prime:
    c = elem % 10
    b = int((elem % 100 - c)/10)
    a = int((elem - b - c)/100)
    mult = a * b * c
    digi_mult_dict[elem] = mult
numero = input("input a number")
for key, value in digi_mult_dict.items():
    if int(value) == int(numero):
        print(key)

列表的数字相乘 python

Multiply digits of number of list python

python

split

list

digits