剑指offer-1

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4 X 4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.

import java.util.ArrayList;
public class Solution {
public ArrayList<Integer> printMatrix(int [][] array) {
ArrayList<Integer> result = new ArrayList<Integer> ();
if(array.length==0) return result;
int rows = array.length;
int cols = array[0].length;
if(cols == 0) return result;
int left=0;
int right=cols-1;
int top=0;
int bottom=rows-1;
while(left <= right && top <= bottom){
//从左到右
for(int i = left; i <= right; ++i){
result.add(array[top][i]);
}
//从上到下
for(int i = top + 1; i <= bottom; ++i){
result.add(array[i][right]);
}
//从右到左
if(top != bottom){
for(int i = right - 1; i >= left; --i){
result.add(array[bottom][i]);
}
}
//从下到上
if(left != right){
for(int i = bottom - 1; i > top; --i){
result.add(array[i][left]);
}
}
left++;
top++;
right--;
bottom--;
}
return result;
}
}