检查具有范围的任何数模数是否为零(Checking if any modulus of number with a range is zero)

检查具有范围的任何数模数是否为零(Checking if any modulus of number with a range is zero)

存在函数d（n），其被定义为n的适当除数之和（小于n的数字，其均匀地划分为n）。 例如，220的适当除数是1,2,4,5,10,11,20,22,44,55和110; 因此d（220）= 284. 284的适当除数是1,2,4,71和142; 所以d（284）= 220。

我想在Ruby中实现这个d（n）函数。 我的第一直觉是使用for循环遍历所有值到n并检查模数。 以下代码有效：

我可以使用这样的for循环来使用它：

def d(n) proper_divisors = [] for i in 1...n if (n % i == 0) proper_divisors.push(i) end end return proper_divisors.inject(:+) end

但是从之前的回答中我了解到it's very rare to use a for loop in Ruby 。 这就是我尝试这个的原因：

def d(n) (1..n).inject(0) { |total| total+ n if (n % (1..n) == 0) } end

因此，从1 to n的值开始， total等于0，并且如果n可以等于1 to n ，则将n加到total 。 部分if (n % (1..n) == 0)不起作用，因为Range can't be coerced into Fixnum (TypeError) 。

我怎样才能实现我对一个范围取一个数的模数，如果它等于零则返回true？

There is a function d(n) which is defined as the sum of proper divisors of n (numbers less than n which divide evenly into n). E.g., the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110; therefore d(220) = 284. The proper divisors of 284 are 1, 2, 4, 71 and 142; so d(284) = 220.

I want to implement this d(n) function in Ruby. My first instinct would be to use a for-loop to loop over all values up to n and check the modulus. The code below works:

I can get it to work with a for-loop like this:

def d(n) proper_divisors = [] for i in 1...n if (n % i == 0) proper_divisors.push(i) end end return proper_divisors.inject(:+) end

But from a previous answer I learned that it's very rare to use a for loop in Ruby. That's why I tried this:

def d(n) (1..n).inject(0) { |total| total+ n if (n % (1..n) == 0) } end

So from the values from 1 to n I start with total equal to 0 and add n to the total if n can be equally divided by a number from 1 to n. The part if (n % (1..n) == 0) does not work since Range can't be coerced into Fixnum (TypeError).

How can I accomplish that I take the modulus of one number against a range and return true if it is equal to zero?

最满意答案

（修复版toro2k的回答）

def d(n) (1..n/2).inject(0) { |total, m| (n % m).zero? ? total + m : total } end d(220) # => 284

Block to inject接受两个参数：集合的累加器和当前元素。 该块应该返回累加器的新值。 在您的代码中，您忽略当前元素（这使您尝试将n除以范围）

(fixed version of toro2k's answer)

def d(n) (1..n/2).inject(0) { |total, m| (n % m).zero? ? total + m : total } end d(220) # => 284

Block to inject accepts two parameters: the accumulator and current element of the collection. This block should return new value of the accumulator. In your code you ignore the current element (which makes you try dividing n by a range)