Implementation and simple analysis of several sorting algorithms in Java

This paper describes the implementation and simple analysis of several sorting algorithms in Java. Share with you for your reference. The details are as follows:

Insertion sort, exchange sort, selection sort, merge sort and other sorting methods have a common feature, that is, they all determine the relative position between elements by comparing the size of elements, that is, the above sorting methods are based on comparison. Next, we will compare and summarize the sorting methods based on comparison. We mainly compare the ranking methods from the aspects of average time complexity, worst time complexity, space complexity and ranking stability.

Sorting method average time complexity worst time complexity space complexity stability direct insertion sorting Ο (n2) Ο (n2) Ο (1) Stable bubble sorting Ο (n2) Ο (n2) Ο (1) Stable quick sort Ο (n log n) Ο (n2) Ο (log n) unstable simple selection sorting Ο (n2) Ο (n2) Ο (1) Unstable heap sort Ο (n log n) Ο (n log n) Ο (1) Unstable merge sort Ο (n log n) Ο (n log n) Ο (n) Steady

In terms of time performance, quick sort has the best actual performance among all sorting algorithms. However, in the worst case, the time performance of quick sort is not as good as heap sort and merge sort. This can be avoided by improving the quick sort. A random quick sort by randomly selecting pivot elements can make the probability of the worst case very small, which can be considered not to exist in practical application. In the comparison between heap sort and merge sort, when n is large, merge sort takes less time, but it requires more auxiliary storage space.

In terms of method stability, most of the time complexity is Ο The sorting of (N2) is a stable sorting method, except for simple selection sorting. Most sorting methods with good time performance, such as quick sort, heap sort and Hill sort, are unstable. Generally speaking, the comparison in the sorting process is between two adjacent elements, and the sorting method is stable.

Moreover, the stability of sorting method is determined by the method itself. For unstable sorting methods, no matter how their description form is, an unstable instance can always be found.

To sum up, none of the sorting methods discussed above is absolutely optimal. In the actual use process, appropriate sorting methods should be selected according to different situations.

I hope this article will be helpful to your Java programming.