选取一个关键码key，一趟排序将要排序的数据分割成独立的两部分，key前的元素都小于key, 靠后的都大于key, 然后再按此方法对这两部分数据分别进行快速排序，整个排序过程可以递归进行，以此达到整个数据变成有序序列。(Select a key key, the two part of a sort to sort the data into independent, key elements are less than key, later than key, then according to the method of the data of the two parts were quick sort, the sorting process can be performed recursively, in order to achieve the data into ordered sequence.)