自己整理的算法 归并排序

Posted 2020-08-07 小竹子kisty

package sort;

public class MergeSort {
	public static void mergeSort(int[] list){
		if(list.length>1){
			int[] firstHalf= new int[list.length/2];
			System.arraycopy(list,0,firstHalf,0,list.length/2);
			mergeSort(firstHalf);
			
			int[] secondHalf = new int[list.length-list.length/2];
			System.arraycopy(list,list.length/2,secondHalf,0,list.length-list.length/2);
			mergeSort(secondHalf);
			
			int[] temp  = merge(firstHalf,secondHalf);
			System.arraycopy(temp, 0, list,0, temp.length );
		}
	}
	
	private static int[] merge(int[] list1,int[] list2){
		int[] temp  = new int[list1.length + list2.length];
		int current1 =0;
		int current2 = 0;
		int current3 = 0;
		
		while(current1<list1.length&&current2<list2.length){
			if(list1[current1]<list2[current2])
				temp[current3++]= list1[current1++];
			else temp[current3++] = list2[current2++];
		}
		
		while(current1<list1.length)  temp[current3++] = list1[current1++];
		while(current2<list2.length)  temp[current3++] = list2[current2++];
		return temp;
		
	}
	
	public static void main(String[] args){
		int[] list ={2,3,2,5,6,1,3,14,12};
		mergeSort(list);
		for(int i =0;i<list.length;i++)
			System.out.print(list[i]+" ");
	}

}