java複習之歸併排序的實現

java複習之歸併排序的實現

package learn;

import java.util.Arrays;

/**
 * 歸併排序，合併次數爲num-1
 */
public class GBSort {
    public static void dis(int[] array,int left,int right,int[] temp){
        if(left<right){
            int mid=(left+right)/2;
            dis(array,left,mid,temp);
            dis(array,mid+1,right,temp);
            merge(array,left,mid,right,temp);
        }
    }
    public static void merge(int[] array,int left,int mid,int right,int[] temp){
        int i=left;
        int j=mid+1;
        int index=0;
        while (i<=mid&&j<=right){
            if(array[i]<=array[j]){
                temp[index]=array[i];
                i++;
                index++;
            }else{
                temp[index]=array[j];
                j++;
                index++;
            }
        }
        while (i<=mid){
            temp[index]=array[i];
            i++;
            index++;
        }
        while(j<=right){
            temp[index]=array[j];
            j++;
            index++;
        }
        int t=0;
        for(int k=left;k<=right;k++){
            array[k]=temp[t];
            t++;
        }
    }
    public static void main(String[] args) {
        int[] array = {8,4,5,7,1,3,6,2};
        int[] temp=new int[array.length];
        dis(array,0,array.length-1,temp);
        System.out.println(Arrays.toString(array));
    }
}