Question

这只是我想到的一个随机场景，如果我有这个阵列：

[3,2,5,6,7,8,9,1,2]

和这个字符串：

'325678912'

我会使用Ruby编写哪些代码来生成：

3*2*5 = 30, 6*7*8 = 336, and 9*1*2 = 18

并将其放入以下数组：

[30,336,18]

抱歉，我忘了把我的代码放回错误的答案：

b = [3,2,5,6,7,8,9,1,2]


first = 0
third = first + 2
array = []
while first<b.length
  prod=1
  b[first..third].each do |x|
    prod*=x.to_i
    array<<prod
  end
  first+=2
  third = first + 2
end

print array

我的另一段代码：

a = '325678912'

number = a.split('')
first = 0
third = first + 2
array = []
while first<number.length
  prod=1
  number[first..third].each do |x|
    prod*=x.to_i
    array<<prod
  end
  first+=2
  third = first + 2
end

print array

对于这两段代码，我得到了这个答案：[3,6,30,5,30,210,7,56,504,9,9,18,2]，我想要的是：[30,336， 18]

有谁能告诉我我的代码有什么问题？

提前谢谢！

Answer 1

使用Enumerable#each_slice：

[3,2,5,6,7,8,9,1,2].each_slice(3).map { |a,b,c| a*b*c }
# => [30, 336, 18]
[3,2,5,6,7,8,9,1,2].each_slice(3).map { |x| x.reduce(:*) }
# => [30, 336, 18]

使用String#chars将字符串转换为单字符串数组。然后使用上面的代码来获得结果：

'325678912'.chars
# => ["3", "2", "5", "6", "7", "8", "9", "1", "2"]
'325678912'.chars.map(&:to_i)
# => [3, 2, 5, 6, 7, 8, 9, 1, 2]
'325678912'.chars.map(&:to_i).each_slice(3).map { |a,b,c| a*b*c }
# => [30, 336, 18]

Answer 2

您的代码，带有评论。

b = [3,2,5,6,7,8,9,1,2]
first = 0
third = first + 2
array = []
while first<b.length
  prod=1
  b[first..third].each do |x|
    prod*=x.to_i  # to_i unnecessary, already integer
    array<<prod   # Ah no. Too early. move this outside the block
  end
  #Here would be fine.
  #And don't forget to reset prod to 1.
  first+=2  #3 ! not 2.
  third = first + 2
end

print array

如何使用Ruby找到数组或字符串中每三个数字的乘积？

2 个答案: