JAVA十大排序算法之归并排序详解

public class MergeSort {
    public static final int[] ARRAY = {8, 5, 6, 4, 3, 1, 7, 2};
    public static int[] sort(int[] array) {
        if (array.length < 2) return array;
        int mid = array.length / 2;
        //分成2组
        int[] left = Arrays.copyOfRange(array, 0, mid);
        int[] right = Arrays.copyOfRange(array, mid, array.length);
        //递归拆分
        return merge(sort(left), sort(right));
    }
    //治---合并
    public static int[] merge(int[] left, int[] right) {
        int[] result = new int[left.length + right.length];
        //i代表左边数组的索引，j代表右边
        for (int index = 0, i = 0, j = 0; index < result.length; index++) {
            if (i >= left.length) {//说明左侧的数据已经全部取完，取右边的数据
                result[index] = right[j++];
            } else if (j >= right.length) {//说明右侧的数据已经全部取完，取左边的数据
                result[index] = left[i++];
            } else if (left[i] > right[j]) {//左边大于右边，取右边的
                int a = right[j++];
                result[index] = a;
            } else {//右边大于左边，取左边的
                result[index] = left[i++];
            }
        }
        return result;
    }
    public static void print(int[] array) {
        for (int i : array) {
            System.out.print(i + "  ");
        }
        System.out.println("");
    }
    public static void main(String[] args) {
        print(ARRAY);
        System.out.println("============================================");
        print(sort(ARRAY));
    }
}