【剑指Offer】【数组】顺时针打印矩阵

class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
        vector<int> ret;
        ret.clear();
        
        if(!matrix.empty())
        {
            int row = matrix.size();
            int col = matrix[0].size();
            
            int top = 0;
            int bottom = row - 1;
            int left = 0;
            int right = col - 1;

            while((top <= bottom) && (left <= right))
            {
                for(int i = left; i <= right; i++)
                {
                    ret.push_back(matrix[top][i]);
                }
                for(int i = top + 1; i <= bottom; i++)
                {
                    ret.push_back(matrix[i][right]);
                }
                for(int i = right - 1 ; i >= left && top < bottom ; i--)    //已经打印过了的不用再打印
                {
                    ret.push_back(matrix[bottom][i]);
                }
                for(int i = bottom - 1; i > top && left < right; i--)    //已经打印过了的不用再打印
                {
                    ret.push_back(matrix[i][left]);
                }
                top++;
                right--;
                bottom--;
                left++;
            }
        }
        return ret;
    }
};