leetcode54

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        if (matrix.empty())
            return vector<int>();

        vector<int> ret;

        //输入矩阵行数
        int m = matrix.size() - 1;

        //输入矩阵的列数
        int n = matrix[0].size() - 1;

        for (int x = 0, y = 0; x <= m && y <= n; x++, y++)
        {
            //输出矩阵首行
            for(int j=y ; j<=n ; ++j)
            {
                ret.push_back(matrix[x][j]);
            }//while


            //输出矩阵最右列
            for (int i = x + 1; i <= m; ++i)
            {
                ret.push_back(matrix[i][n]);
            }//while

            //输出矩阵最底行
            for (int j = n - 1; j >= y && x != m; --j)
            {
                ret.push_back(matrix[m][j]);
            }

            //输出矩阵最左列
            for (int i = m - 1; i > x && y != n; --i)
            {
                ret.push_back(matrix[i][y]);
            }

            m--;
            n--;
        }//for

        return ret;
    }
};

补充一个使用dfs思想的python实现代码：

 1 class Solution:
 2     # matrix类型为二维列表，需要返回列表
 3     def __init__(self):
 4         self.result = []
 5         self.visited = []
 6 
 7     def goRight(self,matrix,i,j,row,column,direct):
 8         if j + 1 < column and self.visited[i][j+1] == 0:
 9             self.result.append(matrix[i][j+1])
10             self.visited[i][j+1] = 1
11             self.dfs(matrix,i,j+1,row,column,direct)
12 
13     def goDown(self,matrix,i,j,row,column,direct):
14         if  i + 1 < row and  self.visited[i+1][j] == 0:
15             self.result.append(matrix[i+1][j])
16             self.visited[i+1][j] = 1
17             self.dfs(matrix,i+1,j,row,column,direct)
18 
19     def goLeft(self,matrix,i,j,row,column,direct):
20         if j - 1 >= 0 and self.visited[i][j-1] == 0:
21             self.result.append(matrix[i][j-1])
22             self.visited[i][j-1] = 1
23             self.dfs(matrix,i,j-1,row,column,direct)
24 
25     def goUp(self,matrix,i,j,row,column,direct):
26         if i - 1 >= 0 and self.visited[i-1][j] == 0:
27             self.result.append(matrix[i-1][j])
28             self.visited[i-1][j] = 1
29             self.dfs(matrix,i-1,j,row,column,direct)
30         
31     def dfs(self,matrix,i,j,row,column,direct):
32         if direct == 0:
33             self.goRight(matrix,i,j,row,column,0)
34             self.goDown(matrix,i,j,row,column,1)
35             self.goLeft(matrix,i,j,row,column,2)
36             self.goUp(matrix,i,j,row,column,3)
37         if direct == 1:
38             self.goDown(matrix,i,j,row,column,1)
39             self.goLeft(matrix,i,j,row,column,2)
40             self.goUp(matrix,i,j,row,column,3)
41             self.goRight(matrix,i,j,row,column,0)
42         if direct == 2:
43             self.goLeft(matrix,i,j,row,column,2)
44             self.goUp(matrix,i,j,row,column,3)
45             self.goRight(matrix,i,j,row,column,0)
46             self.goDown(matrix,i,j,row,column,1)
47         if direct == 3:
48             self.goUp(matrix,i,j,row,column,3)
49             self.goRight(matrix,i,j,row,column,0)
50             self.goDown(matrix,i,j,row,column,1)
51             self.goLeft(matrix,i,j,row,column,2)
52 
53     def spiralOrder(self, matrix):
54         row = len(matrix)
55         if row == 0:
56             return []
57         column = len(matrix[0])
58         self.visited = [[0 for c in range(column)] for r in range(row)]
59         self.result.append(matrix[0][0])
60         self.visited[0][0] = 1
61         self.dfs(matrix,0,0,row,column,0)
62         return self.result
63         # write code here