Spiral Matrix II <leetcode>

 1 class Solution {
 2 public:
 3     vector<vector<int>> result;
 4     vector<vector<int> > generateMatrix(int n) {
 5         int total=n*n;
 6         int x=0;
 7         int y=0;
 8         int direction=0;
 9         result.clear();
10         for(int i=0;i<n;i++)
11         {
12             vector<int> nn;
13             result.push_back(nn);
14             for(int j=0;j<n;j++)
15             {
16                 result[i].push_back(0);
17             }
18         }
19         for(int i=1;i<=total;i++)
20         {
21             if(0==result[x][y])
22             {
23                 result[x][y]=i;
24             }
25             else if(0==direction)
26             {
27                 if(y+1<=n-1&&0==result[x][y+1])
28                 {
29                   result[x][y+1]=i;
30                   y++;
31                 }
32                 else 
33                 {
34                     direction=1;
35                 
36                     i--;
37                 }
38             }
39             else if(1==direction)
40             {
41                 if(x+1<=n-1&&0==result[x+1][y])
42                 {
43                    result[x+1][y]=i;
44                    x++;
45                 }
46                 else
47                 {
48                     direction=2;
49                     i--;
50                 }
51             }
52             else if(2==direction)
53             {
54                 if(y-1>=0&&0==result[x][y-1])
55                 {
56                     result[x][y-1]=i;
57                     y--;
58                 }
59                 else
60                 {
61                     direction=3;
62                     i--;
63                 }
64             }
65             else if(3==direction)
66             {
67                 if(x-1>=0&&0==result[x-1][y])
68                 {
69                     result[x-1][y]=i;
70                     x--;
71                 }
72                 else
73                 {
74                     direction=0;
75                     i--;
76                 }
77             }
78         }
79         return result;
80     }
81 };