19顺时针打印矩阵

顺时针打印矩阵
//题目：输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，如果输入如下矩阵： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
class Solution
{
public:
    vector<int> printMatrix(vector<vector<int>> matrix)
    {
        int rows = matrix.size(); //矩阵的行
        int cols = matrix[0].size(); //矩阵的列
        vector<int> tmpVec;
        //输入的二维数组非法，返回空的数组
        if (rows <= 0 || cols <= 0)
        {
            return tmpVec;
        }
        //左上角为startLeft
        int startLeft = 0;
        //右上角的startRight
        int startRight = cols - 1;
        //上
        int top = 0;
        //下
        int bottom = rows -1;
        while(startLeft <= startRight && top <= bottom)
        {
            //从左向右
            for (int i = startLeft; i<=startRight; ++i)
            {
                tmpVec.push_back(matrix[startLeft][i]);
            }
            //从上到下
            for (int i = top+1; i <= bottom; ++i)
            {
                tmpVec.push_back(matrix[i][startRight]);
            }
            //从右到左(只有top == bottom，表示只有一行，该行也遍历过)
            if(top != bottom)
            {
                for (int i = startRight-1; i >=startLeft; --i)
                {
                    tmpVec.push_back(matrix[bottom][i]);
                }
            }
            //从下向上(只有startLeft == startRight，表示只有列，该列也遍历过)
            if (startLeft != startRight)
            {
                for (int i = bottom-1; i>= top+1 ;--i)
                {
                    tmpVec.push_back(matrix[i][startLeft]);
                }
            }
            startLeft++; 
            top++;
            startRight--;
            bottom--;
        }
        return tmpVec;
    }
};