Validate Credit Card Number

最新推荐文章于 2022-11-05 11:49:06 发布

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最新推荐文章于 2022-11-05 11:49:06 发布

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本文介绍了一种用于验证信用卡号码有效性的Luhn算法实现。通过该算法可以检查输入的信用卡号是否符合基本的有效性规则，包括如何从右至左每隔一位进行加倍处理并判断最终结果是否能被10整除。

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地址：http://www.codewars.com/kata/5418a1dd6d8216e18a0012b2/train/python

In this Kata, you will implement The Luhn Algorithm, which is used to help validate credit card numbers.

Given a positive integer of up to 16 digits, return true if it is a valid credit card number, and false if it is not.

Here is the algorithm:

If there are an even number of digits, double every other digit starting with the first, and if there are an odd number of digits, double every other digit starting with the second. Another way to think about it is, from the right to left, double every other digit starting with the second to last digit.

代码：

def validate(n):
    list = []
    while(n>10):
        list.append(n%10)
        n /= 10
    
    list.append(n)    
    sum = 0
    
    for i in range(0,len(list)):
        if( (len(list)%2 + i%2 ) % 2 == 0):
            list[i] *= 2
            if list[i] > 9:
                list[i] -= 9
        sum += list[i]

    if(sum%10 == 0):
        return 'true'
    else:
        return 'false'