归并排序

package cn.aust.zyw.demo;

/**
 * Created by zyw on 2016/2/15.
 */
public class MergeSort2 {
    public static void main(String args[]){
        int a[]={3,2,5,6,1,7,4};
        mergeSort(a);
        for(int i=0;i<a.length;i++){System.out.print(a[i]+" ");}
    }
    public static void mergeSort(int[] array) {
        sortArray(array, 0, array.length - 1);
    }
    //merge合并
    public static void merge(int a[],int low,int mid,int high){
        int i=low;
        int m=mid+1;
        int k=0;
        int temp[]=new int[high-low+1];
        while(i<=mid&&m<=high){
            if(a[i]>a[m]){
                temp[k++]=a[m++];
            }else{
                temp[k++]=a[i++];
            }
        }

        while (i<=mid){
            temp[k++]=a[i++];
        }
        while (m<=high){
            temp[k++]=a[m++];
        }
        for(k=0,i=low;i<=high;i++,k++){
            a[i]=temp[k];
        }
    }
    //sortArray分组
   public static void sortArray(int[] array, int start, int end) {
        if (start == end) {
            return;
        }

        int sortSize = end - start + 1;
        int seperate;
        if (sortSize % 2 == 0) {
            seperate = start + sortSize / 2 - 1;
        } else {
            seperate = start + sortSize / 2;
        }

        sortArray(array, start, seperate);
        sortArray(array, seperate + 1, end);

        merge(array, start, seperate, end);
    }
}