Spiral Matrix

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

For example,
Given the following matrix:

[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ]]

You should return [1,2,3,6,9,8,7,4,5].

从矩阵的左上角开始，转圈打印矩阵

//http://www.cnblogs.com/ganganloveu/p/4157376.html//剑指offer还是哪里有这个题，解法似乎没这么复杂class Solution {public:    vector<int> spiralOrder(vector<vector<int> > &matrix) {        vector<int> ret;        if(matrix.empty() || matrix[0].empty())            return ret;                int m = matrix.size();        int n = matrix[0].size();        int layer = (min(m,n)+1) / 2;        for(int i = 0; i < layer; i ++)        {            //row i: top-left --> top-right            for(int j = i; j < n-i; j ++)                ret.push_back(matrix[i][j]);                            //col n-1-i: top-right --> bottom-right            for(int j = i+1; j < m-i; j ++)                ret.push_back(matrix[j][n-1-i]);                            //row m-1-i: bottom-right --> bottom-left            if(m-1-i > i)            {                for(int j = n-1-i-1; j >= i; j --)                    ret.push_back(matrix[m-1-i][j]);            }                            //col i: bottom-left --> top-left            if(n-1-i > i)            {                for(int j = m-1-i-1; j > i; j --)                    ret.push_back(matrix[j][i]);            }        }        return ret;    }};