Question

我已经从用户那里获得了输入并将其因素放到新列表中。如何检查列表中的素数。

a=int(input())
b=[]
for x in range(2,a):
    if(a%x)==0:
        b.append(x)
print(b)

Answer 1

在这里您可以打印因子列表，然后遍历因子列表，此程序将打印出素数。除了打印它，您还可以通过将print(n)替换为其他内容来将其附加到另一个列表中。

import math
a=int(input())
b=[]
for x in range(2,a):
    if(a%x)==0:
        b.append(x)
print(b)



def is_prime(n): #calling a function 
    if n == 2:
        print(n) #if one of the factors is 2 it prints it because it is a prime number

    if n % 2 == 0 or n <= 1: # if it is less than one or is a factor of 2 it returns false and does nothing
        return False

    sqr = int(math.sqrt(n)) + 1

    for divisor in range(3, sqr, 2): #checks for other divisors
        if n % divisor == 0:
            return False
    print(n) #otherwise it prints out the number since it is a prime number



for n in b:  #iterates through the list of factors and checks if they are prime
    is_prime(n)

如果我们运行此命令，然后输入10，它将返回以下消息：

[2, 5]
2
5

编辑：输入素数时，它将返回一个空白数组。所以我将代码编辑为：

import math
values = []
def is_prime(n): #calling a function 
    if n == 2:
        values.append(n)

        #print(n) #if one of the factors is 2 it prints it because it is a prime number
        return True
    if n % 2 == 0 or n <= 1: # if it is less than one or is a factor of 2 it returns false and does nothing
        return False

    sqr = int(math.sqrt(n)) + 1

    for divisor in range(3, sqr, 2): #checks for other divisors
        if n % divisor == 0:
            return False
    #print(n) #otherwise it prints out the number since it is a prime number
    values.append(n)
    return True


a=int(input())
b=[]
for x in range(2,a):
    if(a%x)==0:
        b.append(x)
    if is_prime(a)==True: #if the inputted number is prime it automatically appends that number to the list and breaks since prime numbers don't have any other factors
        b.append(a)
        break;

print(b)


for n in b:  #iterates through the list of factors and checks if they are prime
    is_prime(n)
def remove_duplicates(values):  #here it checks for duplicates
    output = []
    seen = set()
    for value in values:
        # If value has not been encountered yet,
        # ... add it to both list and set.
        if value not in seen:
            output.append(value)
            seen.add(value)
    return output

# Remove duplicates from this list.
values = remove_duplicates(values)

print("Here are the prime factors :")    
print(values) #prints out the values

现在，如果输入素数，它将返回：

[7]
Here are the prime factors :
[7]

以及其他任何数字，例如20：

[2, 4, 5, 10]
Here are the prime factors :
[2, 5]

仍将运行。注意：我将其从仅打印数字更改为将数字附加到数组，然后打印出数组。

Answer 2

这里是一个底线，您可以通过更改1和150来更改上下限。将其分配给变量。虽然不如SoA快

[i for i in range(1,150) if all(i%j for j in range(2,int(i**(1/2))+1)) and i != 1]

如何在“列表”中打印素数

2 个答案: