# 面试题29

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。

```
示例 1：

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

示例 2：

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]
```

## 限制：

* 0 <= matrix.length <= 100
* 0 <= matrix\[i].length <= 100

## 注意：本题与主站 54 题相同：[https://leetcode-cn.com/problems/spiral-matrix/](https://leetcode-cn.com/problems/spiral-matrix/)

## Solutions

* See probem 54 for details.

1. **straight forward**

```cpp
class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        int m = matrix.size(); if (!m) return {};
        int n = matrix[0].size();

        vector<int> res;
        auto wit = inserter(res, res.end());
        int lenr, lenc, i = 0, j = 0;

        while (true) {
            if (m <= 0 || n <= 0)
                break;
            lenr = m; lenc = n;
            wit = matrix[i][j];
            while (--lenc) wit = matrix[i][++j];
            while (--lenr) wit = matrix[++i][j];
            if (m > 1 && n > 1) {
                lenr = m - 1; lenc = n;
                while (--lenc) wit = matrix[i][--j];
                while (--lenr > 0) wit = matrix[--i][j];
            }
            j++; m -= 2; n -= 2;
        }

        return res;
    }
};
```
