归并排序

public class Guibingpaixu {
    public static void main(String args[]){
      int num[]=new int[]{4,3,2,1,7,8,9,0,11,23,56,12};
      printnum(num);
      int res[]=new int[num.length];
      guibing(0,num.length-1,num,res);
      printnum(res);
    }
    public static void guibing(int low,int high,int num[],int res[]){
        if(low<high){
            int mid=(low+high)/2;
            int l_res[]=new int[mid-low+1];
            int r_res[]=new int[high-mid];
            guibing(low,mid,num,l_res);
            guibing(mid+1,high,num,r_res);
            merge(l_res,r_res,res);
        }else{
            res[0]=num[low];
        }
    }
    public static void merge(int l_res[],int r_res[],int res[]){
        int i=0,j=0;
        while(i<l_res.length && j<r_res.length){
            if(l_res[i]>r_res[j]){
                res[i+j]=r_res[j];
                j++;
            }else{
                res[i+j]=l_res[i];
                i++;
            }
        }
        while(i<l_res.length){
            res[i+j]=l_res[i];
            i++;
        }
        while(j<r_res.length){
            res[i+j]=r_res[j];
            j++;
        }
    }
    public static void printnum(int num[]){
        for(int i=0;i<num.length;i++){
            System.out.print(num[i]+" ");
        }
        System.out.println();
    }
}