Spiral Matrix II

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        vector<int> ans;
        for(int i=1;i<=(n*n);i++)
        {
            ans.push_back(i);
        }
        int p=0;
        vector<vector<int>> matrix(n, vector<int>(n, 0));

            int top = 0, down = n - 1, left = 0, right = n - 1;
            while (true) {
                for (int j = left; j <= right; j++)
                {
                   matrix[top][j]=ans[p];
                   p++;
                }
                if (++top > down)
                {
                   break;
                }
                for (int i = top; i <= down; i++)
                {
                  matrix[i][right]=ans[p];
                  p++;
                }
                if (--right < left)
                {
                  break;
                }
                for (int j = right; j >= left; j--)
                {
                 matrix[down][j]=ans[p];
                 p++;
                }

                if (--down < top)
                {
                  break;
                }
                for (int i = down; i >= top; i--)
                {
                  matrix[i][left]=ans[p];
                  p++;
                }
                if (++left > right)
                {
                 break;
                }

    }
    return matrix;
    }
};