剑指offer系列17---顺时针打印矩阵（不是很懂）

 1 package com.exe4.offer;
 2 
 3 import java.util.ArrayList;
 4 /**
 5  * 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 
 6  * 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
 7  * @author WGS
 8  *
 9  */
10 public class PrintArraysInCircle {
11 
12     public ArrayList<Integer> printArraysClock(int[][] arrs){
13          int rows=arrs.length;
14          int columns=arrs[0].length;
15         if(arrs==null || rows<=0 || columns<=0)
16             return null;
17         
18          ArrayList<Integer> list=new ArrayList<Integer>();
19          //起点坐标
20          int count=0;
21          while(columns>count*2 && rows>count*2){
22              printArraysInCircle(list,arrs,columns,rows,count);
23              count++;
24          }
25          return list;
26     }
27     
28     
29         
30     public void printArraysInCircle(ArrayList<Integer> list,int[][] arrs,int columns,int rows,int count) {
31         int endX=columns-1-count;
32         int endY=rows-1-count;
33         int number=0;
34         
35         //从左到右打印》》》》》》
36         for(int i=count;i<=endX;i++){
37             list.add(arrs[count][i]);
38         }
39         //从上到下打印
40         if(count<endX){
41             for(int i=count+1;i<=endY;i++){
42                 list.add(arrs[i][endX]);
43             }
44         }
45         //从右到左
46         if(count<endX && count<endY){
47             for(int i=endX-1;i>=count;i--){
48                 list.add(arrs[endY][i]);
49             }
50         }
51         //从下到上
52         if(count<endX && count<endY-1){
53             for(int i=endY-1;i>=count+1;i--){
54                 list.add(arrs[i][count]);
55             }
56         }
57         
58     }
59 
60 
61 
62     public static void main(String[] args) {
63         // TODO Auto-generated method stub
64              int[][] arrs = new int[4][4];
65              arrs[0] = new int[]{1,2,3,4};
66              arrs[1] = new int[]{5,6,7,8};
67              arrs[2] = new int[]{9,10,11,12};
68              arrs[3] = new int[]{13,14,15,16};
69            // matrix[4] = new int[]{17,18,19,20};
70             
71             PrintArraysInCircle p = new PrintArraysInCircle();
72             ArrayList<Integer> list = p.printArraysClock(arrs);
73             for (Integer integer : list) {
74                 System.out.print(integer+" ");
75             }
76     }
77 
78 }