1 #include<iostream>
 2 #include<vector>
 3 using namespace std;
 4 int side(vector<vector<int>>&amp; matrix, vector<int>& result, int m, int n, int up, int down, int left, int right) {
 5     if (matrix.empty() || matrix[0].empty()) return {};
 6     for (int i = left; i <= right; i++) {
 7         result.push_back(matrix[up][i]);
 8     }
 9     if (++up > down) {
10         return 0;
11     }
12     for (int i = up; i <= down; i++) {
13         result.push_back(matrix[i][right]);
14     }
15     if (--right < left) {
16         return 0;
17     }
18     for (int i = right; i >= left; i--) {
19         result.push_back(matrix[down][i]);
20     }
21     if (--down < up) {
22         return 0;
23     }
24     for (int i = down; i >= up; i--) {
25         result.push_back(matrix[i][left]);
26     }
27     if (++left > right) {
28         return 0;
29     }
30     side(matrix, result, m, n, up, down, left, right);
31     return 0;
32 }
33 class Solution {
34 public:
35     vector<int> spiralOrder(vector<vector<int>>& matrix) {
36         vector<int> result;
37         int m = matrix.size(), n = matrix[0].size();
38         int up = 0, down = m - 1, left = 0, right = n - 1;
39         side(matrix, result, m, n, up, down, left, right);
40         return result;
41     }
42 };
43 int main() {
44     vector<vector<int>> matrix = { {1, 2, 3,4},{5,6,7,8},{9,10,11,12},{13,14,15,16} };
45     Solution sol; 
46     vector<int> result=sol.spiralOrder(matrix);
47     for (int i = 0; i < result.size(); i++) {
48         cout << result[i]<<endl;
49     }
50 
51 }@H_412_360@