螺旋矩阵

给定一个包含 m x n 个要素的矩阵，（m 行, n 列），按照螺旋顺序，返回该矩阵中的所有要素。

您在真实的面试中是否遇到过这个题？ 

Yes

样例

给定如下矩阵：

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

应返回 [1,2,3,6,9,8,7,4,5]。

class Solution {
public:
    /**
     * @param matrix a matrix of m x n elements
     * @return an integer array
     */
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        // Write your code here
        vector<int> result;
	    int m = matrix.size();
	    if (m < 1)
	    {
		    return result;
	    }
	    int n = matrix[0].size();
	    if (n < 1)
	    {
		    return result;
	    }

	    int left = 0;
	    int top = 0;
	    int right = n-1;
	    int bottom = m-1;
	    int total = m*n;
	    int num = 0;
	    int i = 0;
	    int j = 0;

	    while (num < total)
	    {
		    while (j <= right)
		    {
			    result.push_back(matrix[i][j]);
			    j++;
			    num++;
		    }
		    if (num == total)
		    {
		        break;
		    }
		    i++;
		    j = right;
		    top++;
		    while (i <= bottom)
		    {
			    result.push_back(matrix[i][j]);
			    i++;
			    num++;
		    }
		    if (num == total)
		    {
		        break;
		    }
		    i = bottom;
		    j--;
		    right--;
		    while (j >= left)
		    {
			    result.push_back(matrix[i][j]);
			    j--;
			    num++;
		    }
		    if (num == total)
		    {
		        break;
		    }
		    i--;
		    j = left;
		    bottom--;
		    while (i >= top)
		    {
			    result.push_back(matrix[i][j]);
			    i--;
			    num++;
		    }
		    if (num == total)
		    {
		        break;
		    }
		    i = top;
		    j++;
		    left++;
	    }

	    return result;
    }
};