問題描述

我想做一個python程序來生成一個數的質數之和，但是程序沒有給出正確的結果，請告訴我為什么.

I am tying to make a python program that will generate the sum of primes for a number, but the program is not giving the correct result,please tell me why.

b=1
#generates a list of numbers.
while b<100:
    b=b+1
    x = 0.0
    a = 0
    d = 0
    #generates a list of numbers less than b. 
    while x<b:
        x=x+1
        #this will check for divisors. 
        if (b/x)-int(b/x) == 0.0:
            a=a+1
        if a==2:
            #if it finds a prime it will add it.
            d=d+b
print d 

我讓它成功生成了一個素數列表，但我無法添加素數.

I made it generate a list of primes successfully, but i could not get the primes to add.

這是我用來生成素數列表的代碼.

This is the code that i used to generate a list of primes.

b=1
while b<1000:
    b=b+1
    n = b
    x = 0.0
    a = 0
    while x<n:
        x=x+1
        if (n/x)-int(n/x) == 0.0:
            a=a+1
    if a==2:
        print b

推薦答案

您的 d 變量在您的外部循環的每次迭代中被重置.將初始化移出該循環.

Your d variable is being reset during each iteration of your outer loop. Move the initialization out of that loop.

此外，a == 2 檢查應該只在外循環的每次迭代中發生一次.將其移出內循環.

Additionally, the a == 2 check should only occur once per iteration of the outer loop. Move it out of the inner loop.

b=1
d = 0
#generates a list of numbers.
while b<100:
    b=b+1
    x = 0.0
    a = 0
    #generates a list of numbers less than b. 
    while x<b:
        x=x+1
        #this will check for divisors. 
        if (b/x)-int(b/x) == 0.0:
            a=a+1
    if a==2:
        #if it finds a prime it will add it.
        d=d+b
print d 

結果:

1060

在我們處理它的同時，讓我們嘗試清理代碼以使其更易于理解.您可以將內部循環移動到自己的函數中，以便讀者更清楚地了解其用途:

While we're at it, let's try cleaning up the code so it's more comprehensible. You can move the inner loop into its own function, so readers can more clearly understand its purpose:

def is_prime(b):
    x = 0.0
    a = 0
    while x<b:
        x=x+1
        #this will check for divisors. 
        if (b/x)-int(b/x) == 0.0:
            a=a+1
    if a==2:
        return True
    else:
        return False

b=1
d=0
#generates a list of numbers.
while b<100:
    b=b+1
    if is_prime(b):
        d=d+b
print d

使用描述它們所代表的變量名稱也很有用:

It's also useful to use variable names that describe what they represent:

def is_prime(number):
    candidate_factor = 0
    amount_of_factors = 0
    while candidate_factor<number:
        #A += B is equivalent to A = A + B
        candidate_factor += 1
        #A little easier way of testing whether one number divides another evenly
        if number % candidate_factor == 0:
            amount_of_factors += 1
    if amount_of_factors == 2:
        return True
    else:
        return False

number=1
prime_total=0
#generates a list of numbers.
while number<100:
    number += 1
    if is_prime(number):
        prime_total += number
print prime_total

for 循環比增加計數器的 while 循環更符合規范:

for loops are more idomatic than while loops that increment a counter:

def is_prime(number):
    amount_of_factors = 0
    for candidate_factor in range(1, number+1):
        if number % candidate_factor == 0:
            amount_of_factors += 1
    if amount_of_factors == 2:
        return True
    else:
        return False

prime_total=0
#generates a list of numbers.
for number in range(2, 101):
    if is_prime(number):
        prime_total += number
print prime_total

如果您覺得大膽，可以使用列表推導來減少您使用的循環數量:

If you're feeling bold, you can use list comprehensions to cut down on the number of loops you use:

def is_prime(number):
    factors = [candidate_factor for candidate_factor in range(1, number+1) if number % candidate_factor == 0]
    return len(factors) == 2

#generates a list of numbers.
primes = [number for number in range(2, 101) if is_prime(number)]
prime_total = sum(primes)
print prime_total

這篇關于python素數之和的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！