leetcode刷题（119）——54.螺旋矩阵

输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
输出：[1,2,3,6,9,8,7,4,5]

输入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
输出：[1,2,3,4,8,12,11,10,9,5,6,7]

class Solution {
    public List<Integer> spiralOrder(int[][] matrix) {
        int l = 0, r = matrix[0].length - 1, t = 0, b = matrix.length - 1;
        List<Integer> list = new ArrayList<>();
        int toal = matrix.length * matrix[0].length;
        int num = 1;
        while (num <= toal) {
            for (int i = l; i <= r && num <= toal  ; i++) { //从左到右
                list.add(matrix[t][i]);
                num++;
            }
            t++;
            for (int i = t; i <= b && num <= toal ; i++) { //从上到下
                list.add(matrix[i][r]);
                num++;
            }
            r--;
            for (int i = r; i >= l && num <= toal ; i--) { //从右到左
                list.add(matrix[b][i]);
                num++;
            }
            b--;
            for (int i = b; i >= t && num <= toal ; i--) { //从下到上
                list.add(matrix[i][l]);
                num++;
            }
            l++;
        }
        return list;
    }
}