八大排序算法之（七）歸併排序

public class MergingSort {

int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};  
	
	public MergingSort(){  
	 sort(a,0,a.length-1);  
	 for(int i=0;i<a.length;i++)  
	    System.out.println(a[i]);  
	}  
	
	public void sort(int[] data, int left, int right) {  
	 // TODO Auto-generatedmethod stub  
	 if(left<right){  
	     //找出中間索引  
	     int center=(left+right)/2;  
	     //對左邊數組進行遞歸  
	     sort(data,left,center);  
	     //對右邊數組進行遞歸  
	     sort(data,center+1,right);  
	     //合併  
	     merge(data,left,center,right);         
	 }  
	
	}  
	
	public void merge(int[] data, int left, int center, int right) {  
	 // TODO Auto-generatedmethod stub  
	 int [] tmpArr=new int[data.length];  
	 int mid=center+1;  
	 //third記錄中間數組的索引  
	 int third=left;  
	 int tmp=left;  
	 while(left<=center&&mid<=right){  
	     //從兩個數組中取出最小的放入中間數組  
	     if(data[left]<=data[mid]){  
	         tmpArr[third++]=data[left++];  
	     }else{  
	         tmpArr[third++]=data[mid++];  
	     }  
	
	 }  
	
	 //剩餘部分依次放入中間數組  
	 while(mid<=right){  
	     tmpArr[third++]=data[mid++];  
	 }  
	
	 while(left<=center){  
	     tmpArr[third++]=data[left++];  
	 }  
	
	 //將中間數組中的內容複製回原數組  
	 while(tmp<=right){  
	     data[tmp]=tmpArr[tmp++];  
	 }  
	 System.out.println(Arrays.toString(data));  
	}  
	
	public static void main(String[] args) {
		new MergingSort();
	}
}