归并（非递归）

 分治思想：一一归并，二二归并，四四归并，八八归并......

package com.mahai.sort;

import java.util.Scanner;

public class MergeNR {
	private static String[] aux;
	//TODO 一一归并，二二归并，四四归并，八八归并......
	public static void sort(String[] a) {
		int N = a.length;
		aux = new String[N];
		for (int sz = 1; sz < N; sz += sz) {//子数组大小
			for (int low = 0; low < N-sz; low += 2*sz ) {
				merge(a, low, low+sz-1, Math.min(low+2*sz-1, N-1));
			}
		}
	}
	// TODO 归并 将a[low..mid]和a[mid+1..hi]归并和排序
	public static void merge(String[] a, int low, int mid, int hi) {
		int i = low, j = mid + 1;
		for (int j2 = low; j2 <= hi; j2++)
			aux[j2] = a[j2];
		for (int j2 = low; j2 <= hi; j2++)
			if (i > mid)
				a[j2] = aux[j++];
			else if (j > hi)
				a[j2] = aux[i++];
			else if (less(aux[j], aux[i]))
				a[j2] = aux[j++];
			else
				a[j2] = aux[i++];
	}

	// TODO 比较大小
	private static boolean less(String a, String b) {
		return a.hashCode() < b.hashCode();
	}

	// TODO show方法
	private static void show(String[] a) {
		for (int i = 0; i < a.length; i++) {
			System.out.print(a[i] + " ");
		}
		System.out.println();
	}

	// TODO main方法
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		System.out.println("请输出数组长度：");
		int length = s.nextInt();
		String[] a = new String[length];
		for (int j = 0; j < length; j++) {
			System.out.println("请输入第" + (j + 1) + "个数组元素：");
			a[j] = s.next();
		}
		System.out.println("输入完毕！");
		s.close();
		show(a);
		sort(a);
		show(a);
	}
}