Question

我试图理解ruby中的以下冒泡排序实现。我不明白的主要是使用sorted变量。我评论了我觉得最令人困惑的部分，我非常感谢sorted变量使用的解释。

def bubble_sort(arr)
    sorted = false  #set sorted to false because array is not yet sorted..correct?
    until sorted  #this is where I get confused..this means until false..right? Shouldn't it be until true?
        sorted = true #this makes a little more sense.  Now sorted = true, so until = false isn't satisfied
        (arr.count - 1).times do |i|
            if arr[i] > arr[i + 1]
                arr[i], arr[i+1] = arr[i+1], arr[i]
                sorted = false #so now sorted = false, shouldn't this mean the loop stops? How does the program go through more than one iteration of the until loop?
            end
        end
    end
    arr
end

Answer 1

until sorted就像在说while !sorted

考虑到这一点，我认为这应该更有意义。

Ruby对if语句有类似的构造。你可以说 unless foo表示与if !foo相同。有时这些类型的表达式会让人感到困惑，因为它们可能是双重否定。

但是如果你只是大声读出代码那就应该有意义了......

直到数组排序...继续排序...

Answer 2

你走在正确的轨道上，但until关键字的行为与你的直觉相反。代码

until X
    action

应该在“X成立之前阅读，重复action”，换句话说，只要action为假，就会重复X。“

Answer 3

def bubble_sort(arr)
    sorted = false  #sorted varriable is equal to false
    until sorted  #until sorted variable is true, this code will run
        sorted = true #sorted variable is now true
        (arr.count - 1).times do |i|
            if arr[i] > arr[i + 1]
                arr[i], arr[i+1] = arr[i+1], arr[i]
                sorted = false #sorted variable is now set to false, so loop will run again.
            end
        end
    end
    arr
end

我无法理解这个红宝石冒泡排序实现的部分内容？

3 个答案: