蛇形排列 非遞歸

/**
 * 蛇形排列的算法實現
 * 
 * 蛇形排列
 * 
 * 輸入4
 * 輸出：
 * 1   2   3   4
 * 12  13  14  5
 * 11  16  15  6
 * 10  9   8   7
 * 
 * 輸入5：
 * 
 * 1	2	3	4	5
 * 16   17  18  19  6
 * 15   24  25  20  7
 * 14	23	22	21  8
 * 	13	12	11	10	9
 */

package com.my.alg;

import java.io.*;
import java.util.*;

public class SnakeSort {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		
		int i = sc.nextInt();	
		int[][] arr = new int[i][i];
		
		snakeSort(arr);
		//打印
		for(int m = 0;m < i; m ++){
			for(int n = 0; n < i; n ++){
				System.out.print(arr[m][n] + "       ");
			}
			System.out.println();
		}
	}
	
	
	public static void snakeSort(int[][] a){
		int i = a.length;//數組的邊
		int increase = 1;//從一開始計數
		int now = 0;//循環次數 
		int which = 0;//標記這是第幾層，有外到內，0 1 2....
		//從最外層開始排列
		
		while(now < i){
			//上面的橫排填充
			for(int k = 0 + which;k < i - which; k ++){
				
				System.out.println(which + "  " + k);
				a[which][k] = increase;
				increase ++;
			}
			//右側的豎排填充
			for(int k = which + 1 ; k < i - which; k++){
				
				System.out.println(k + "  " + (i - which -1));
				a[k][i - which -1] = increase;
				increase ++;
			}
			//下面的橫排填充
			for(int k = i - 2 -which ; k >=which ; k --){
				
				System.out.println((i - which -1) + "  " + k);
				a[i-1 - which][k] = increase;
				increase ++;
			}
			//左側的豎排填充
			for(int k = i - 2 -which ; k > which ; k --){
				
				System.out.println(k + "  " + which);
				a[k][which] = increase;
				increase ++;
			}
			//層數加一
			which ++;
			//進行下一個循環
			now += 2;
		}	
	}
}