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+" ");
             }
     }

 }