/**
 *
 * @param matrix int整型二维数组
 * @return int整型一维数组
 */
func spiralOrder(matrix [][]int) []int {
    res := []int{}
    if len(matrix) == 0 {return res}
    
    t := 0
    b := len(matrix) - 1
    l := 0
    r := len(matrix[0]) - 1
    for t <= b && l <= r {
    	//左->右
        for i := l; i <= r; i++ {
            res = append(res, matrix[t][i])
        }
        t++
        //上->下
        for i := t; i <= b; i++ {
            res = append(res, matrix[i][r])
        }
        r--
        //就一行一列,则直接停
        if t > b || l > r {
            break
        }
        //右->左
        for i := r; i >= l; i-- {
            res = append(res, matrix[b][i])
        }
        b--
        //下->上
        for i := b; i >= t; i-- {
            res = append(res, matrix[i][l])
        }
        l++
    }
    return res
}