排序算法

选择排序

 

public class MySelectionSort {


    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            int[] array = generateRandomArray(10, 10);
            System.out.println("随机数组：" + Arrays.toString(array));
            int[] copyArray = Arrays.copyOf(array, array.length);
            Arrays.sort(copyArray);
            System.out.println("Arrays工具类排序：" + Arrays.toString(copyArray));
            selectionSort(array);
            System.out.println("选择排序法排序：" + Arrays.toString(array));
            IntArrayComparator intArrayComparator = new IntArrayComparator();
            int compare = intArrayComparator.compare(copyArray, array);
            if (compare == 0){
                System.out.println("----------------------------排序成功------------------------");
            }else{
                System.out.println("----------------------------排序失败------------------------");
                throw new RuntimeException("排序失败");
            }
        }

    }

    /**
     * 生成一个[-maxValue,maxValue]的随机数组
     *
     * @param maxSize  最大长度
     * @param maxValue 最大值
     * @return 随机数组
     */
    private static int[] generateRandomArray(int maxSize, int maxValue) {
        int[] array = new int[maxSize];
        for (int i = 0; i < maxSize; i++) {
            array[i] = (int) ((maxValue + 1) * Math.random()) - (int) ((maxSize + 1) * Math.random());
        }
        return array;
    }

    /**
     * 排序数组
     *
     * @param array
     */
    private static void selectionSort(int[] array) {
        //比较流程
        //比较0->1,2,3,4...array.length-1
        //比较1->2,3,4,5...array.length-1
        //比较2->3,4,5,6...array.length-1
        //.
        //.
        //.
        //比较array.length-2->array.length-1

        //最外层[0,array.length-2]
        for (int i = 0; i < array.length-1; i++) {
            int minIndex = i;
            //内层[比最外层下标大一,array.length-1]
            for (int j = i + 1; j < array.length; j++) {
                if (array[minIndex] > array[j]) {
                    minIndex = j;
                }
            }
            swap(array, i, minIndex);
        }
    }

    public static void swap(int[] array, int i, int j) {
        if(i!=j){
            int swap = array[i];
            array[i] = array[j];
            array[j] = swap;
        }
    }

    public static class IntArrayComparator implements Comparator<int[]> {
        @Override
        public int compare(int[] o1, int[] o2) {
            if (o1 == null || o2 == null) {
                throw new RuntimeException("比较的两个数据不能为null");
            }
            if (o1.length != o2.length) {
                return -1;
            }
            for (int i = 0; i < o1.length; i++) {
                if (o1[i] != o2[i]) {
                    return 1;
                }
            }
            return 0;
        }
    }
}