说明：  冒泡排序法重复地走访过要排序的数列，一次比较两个元素，如果他们的顺序错误就把他们交换过来。走访数列的工作是重复地进行直到没有再需要交换，也就是说该数列已经排序完成。
(Bubble sorting repeatedly visits the sequence to be sorted, comparing two elements at once, exchanging them if they are in the wrong order. The sequence of visits is repeated until no more exchanges are required, ie the sequence has been sorted.)