排序算法之归并排序

public class MergeSortTest {
    public static void main(String[] args){
        int[] arrs = new int[]{3,5,6,2,4,1,6,8,4,3,0};
        mergeSort(arrs,0,arrs.length - 1);
        System.out.println(Arrays.toString(arrs));
    }

    public static void mergeSort(int[] arrs,int begin,int end){
        int middle = arrs.length / 2;       //一分为二

        //分别初始化左右两边数组
        int[] left = new int[middle - begin];
        int[] right = new int[end - middle + 1];

        for(int i = 0; i < middle - begin;i++){
            left[i] = arrs[i + begin];
        }

        for(int i = 0; i < end - middle + 1; i++){
            right[i] = arrs[i + middle];
        }

        //分别对左右两边数组作归并
        if(left.length > 1) mergeSort(left,0,left.length - 1);
        if(right.length > 1) mergeSort(right,0,right.length - 1);

        //合并左右两边数组
        merge(arrs,left,right);

    }

    //执行merge的前提是left与right都已经排好序
    public static void merge(int[] arrs,int[] left,int[] right){
        int m = 0;
        int n = 0;
        for(int j = 0; j < arrs.length;j++){
            if(m == left.length){
                arrs[j] = right[n];
                n++;
                continue;
            }
            if(n == right.length){
                arrs[j] = left[m];
                m++;
                continue;
            }
            if(left[m] < right[n]){
                arrs[j] = left[m];
                m++;
            }else{
                arrs[j] = right[n];
                n++;
            }
        }
    }

}