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].

只适合方阵的C++实现代码：

vector<int> spiralOrder(vector<vector<int> > &matrix)
    {
        if(matrix.empty()||matrix[0].empty())
            return vector<int>();
        vector<int> ret;
        int n=matrix.size();
        int count=n*n;
        int i=0;
        int j=0;
        while(count)
        {
            if(count==1)
            {
                ret.push_back(matrix[i][j]);
                break;
            }
            for(; j<n-i-1; j++)
            {
                ret.push_back(matrix[i][j]);
                count--;
            }
            for(; i<j; i++)
            {
                ret.push_back(matrix[i][j]);
                count--;
            }
            for(; j>n-i-1; j--)
            {
                ret.push_back(matrix[i][j]);
                count--;
            }
            for(; i>j; i--)
            {
                ret.push_back(matrix[i][j]);
                count--;
            }
            i++;
            j++;
        }
        return ret;
    }