LeetCode_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].

　　注意几点： 1)spiral 总共转了几圈 2) 最后一圈的时候如果是“横”“竖”需要处理好边界

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int> > &matrix) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
      　vector<int> res;
        int rows = matrix.size();
        if(rows == 0) return res;
        int columns = matrix[0].size();
        if( columns ==0) return res;

        int lays = rows > columns ? (columns+1)/2 : (rows+1) /2; 
        bool single =  rows > columns ? columns%2 :rows%2 ;
        for(int lay = 0; lay < lays ; lay++)
        {
            int topRow = lay;
            int rightColumn = columns  - 1 - lay;

            //process the top row 
            for(int i = lay ; i <= rightColumn ; i++)
                res.push_back(matrix[topRow][i]);
            //process the right column ,not include the first of the right column element 
            for(int i = lay +1 ; i <= rows - 1 - lay ; i++)
                res.push_back(matrix[i][rightColumn]);
            
            if(lay == lays -1 && single)
                 continue ;
            //process the bottom row, not include the last of the bottom row element
            for(int i = rightColumn - 1 ;i >= lay ; i--)
                res.push_back(matrix[rows-1-lay][i]);

            //process the left;
            for(int i = rows - 1 - lay -1  ;i > lay ; i--)
                res.push_back(matrix[i][lay]);

        }

        return res;
    }
};