合并算法

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);
			
			//merge sort the second half
			int secondHalfLength = list.length - list.length / 2;
			int[] secondHalf = new int [secondHalfLength];
			
			System.arraycopy(list, list.length / 2, secondHalf	, 0, secondHalfLength);
			mergeSort(secondHalf);
			
			//Merge firstHalf with second half
			
			int[] temp = merge(firstHalf,secondHalf);
			System.arraycopy(temp, 0, list, 0, temp.length);
		}
	}
	/** Merge two sorted lists*/
	
	private static int [] merge(int[] list1,int [] list2)
	{
		int [] temp = new int[list1.length + list2.length];
		int current1 = 0; //Current index in list1
		int current2 = 0; //Current index in list2
		int current3 = 0; //Current index in list3
		
		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,-2,3,14,12};
		mergeSort(list);
		for (int i = 0; i < list.length; i++) {
			System.out.print("  "+list[i]);
			
		}
		
	}

}