leetcode59 Spiral Matrix II

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n = 3,

You should return the following matrix:

[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        vector<vector<int> > ans;
        
        if(n<=0)
            return ans;
        
        vector<int> temp(n,0);
        for(int i=0;i<n;i++)
        {
            ans.push_back(temp);
        }
        
        int xmin=0,ymin=0,xmax=n-1,ymax=n-1;
        
        int total=n*n;
        
        ans[0][0]=1;
        int dir=1;
        int x=0,y=0;
        int count=1;
        
        while(count<total)
        {
            if(dir==1)
            {
               if(y+1>ymax)
               {
                   xmin++;
                   dir=2;
               }
               else
               {
                   y++;
                   count++;
                   ans[x][y]=count;
               }
            }
            else if(dir==2)
            {
               if(x+1>xmax)
               {
                   ymax--;
                   dir=3;
               }
               else
               {
                   x++;
                   count++;
                   ans[x][y]=count;
               }
            }
            else if(dir==3)
            {
               if(y-1<ymin)
               {
                   xmax--;
                   dir=4;
               }
               else
               {
                   y--;
                   count++;
                   ans[x][y]=count;
               }
            }
            else
            {
               if(x-1<xmin)
               {
                   ymin++;
                   dir=1;
               }
               else
               {
                   x--;
                   count++;
                   ans[x][y]=count;
               }
            }
        }
        return ans;
    }
};