剑指offer系列17---顺时针打印矩阵（不是很懂）

package com.exe4.offer;

import java.util.ArrayList;
/**
 * 17【题目】输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，如果输入如下矩阵： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 
 * 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
 * @author WGS
 *
 */
public class PrintArraysInCircle {

    public ArrayList<Integer> printArraysClock(int[][] arrs){
         int rows=arrs.length;
         int columns=arrs[0].length;
        if(arrs==null || rows<=0 || columns<=0)
            return null;
        
         ArrayList<Integer> list=new ArrayList<Integer>();
         //起点坐标
         int count=0;
         while(columns>count*2 && rows>count*2){
             printArraysInCircle(list,arrs,columns,rows,count);
             count++;
         }
         return list;
    }
    
    
        
    public void printArraysInCircle(ArrayList<Integer> list,int[][] arrs,int columns,int rows,int count) {
        int endX=columns-1-count;
        int endY=rows-1-count;
        int number=0;
        
        //从左到右打印》》》》》》
        for(int i=count;i<=endX;i++){
            list.add(arrs[count][i]);
        }
        //从上到下打印
        if(count<endX){
            for(int i=count+1;i<=endY;i++){
                list.add(arrs[i][endX]);
            }
        }
        //从右到左
        if(count<endX && count<endY){
            for(int i=endX-1;i>=count;i--){
                list.add(arrs[endY][i]);
            }
        }
        //从下到上
        if(count<endX && count<endY-1){
            for(int i=endY-1;i>=count+1;i--){
                list.add(arrs[i][count]);
            }
        }
        
    }



    public static void main(String[] args) {
        // TODO Auto-generated method stub
             int[][] arrs = new int[4][4];
             arrs[0] = new int[]{1,2,3,4};
             arrs[1] = new int[]{5,6,7,8};
             arrs[2] = new int[]{9,10,11,12};
             arrs[3] = new int[]{13,14,15,16};
           // matrix[4] = new int[]{17,18,19,20};
            
            PrintArraysInCircle p = new PrintArraysInCircle();
            ArrayList<Integer> list = p.printArraysClock(arrs);
            for (Integer integer : list) {
                System.out.print(integer+" ");
            }
    }

}