学步园

import java.util.Scanner;

public class CMerge {

	private int[] a;
	private int size;
	private int[] b;//辅助临时数组

	public static void main(String[] args) {
		CMerge merge = new CMerge();
		merge.input();
		merge.display();
		merge.MergeSort(0, merge.getSize()-1);
		merge.display();
	}

	public void MergeSort(int low, int high) {
		if (low == high) {
			return;
		}
		int mid = (low + high) / 2;
		MergeSort(low, mid);
		MergeSort(mid + 1, high);
		merge(low, mid, high);
	}

	private void merge(int low, int mid, int high) {
		int i, j, k;
		i = low;
		j = mid + 1;
		k = 0;
		while (i <= mid && j <= high) {
			b[k++] = a[i] < a[j] ? a[i++] : a[j++];
		}
		while (i <= mid) {
			b[k++] = a[i++];
		}
		while (j <= high) {
			b[k++] = a[j++];
		}
		/*将low-high这个区间内的数字排序完后，重新赋值回原数组对应区间位置，等待下一次的归并排序*/
		for (i = low, k = 0; i <= high; i++) {
			a[i] = b[k++];
		}
	}

	public void input() {
		System.out.println("数组大小:");
		Scanner scan = new Scanner(System.in);
		size = scan.nextInt();
		a = new int[size];
		b = new int[size];
		System.out.println("数组元素");
		for (int i = 0; i < a.length; i++) {
			a[i] = scan.nextInt();
		}
		System.out.println("输入完成");
	}

	public void display() {
		for (int i = 0; i < b.length; i++) {
			System.out.print(a[i] + " ");
		}
		System.out.println();
	}

	public int getSize() {
		return size;
	}
}