每日算法之四十一：Spiral Matrix II （螺旋矩阵）

class Solution {
public:
    vector<vector<int> > generateMatrix(int n) {
        vector<vector<int> > matrix;
        if(n < 0)
            return matrix;
        int **m = new int*[n];
        for(int i = 0; i < n; i++)
        {
            m[i] = new int[n];
            memset(m[i], 0, sizeof(int)*n);
        }
        int currentnum = 1;
        int loop = 0;
        while(loop < (n+1)/2)
        {
            int tmp = n - 1 - loop;
            for(int i = loop; i <= tmp; i++)
                m[loop][i] = currentnum++;
            for(int i = loop + 1; i <= tmp; i++)
                m[i][tmp] = currentnum++;
            for(int i = tmp - 1; i >= loop; i--)
                m[tmp][i] = currentnum++;
            for(int i = tmp - 1; i >= loop + 1; i--)
                m[i][loop] = currentnum++;
            loop++;
        }
        for(int i = 0; i < n; i++)
        {
            vector<int> tmp;
            for(int j = 0; j < n; j++)
                tmp.push_back(m[i][j]);
            matrix.push_back(tmp);
        }
        for(int i = 0; i < n; i++)
            delete[] m[i];
        delete[] m;
        return matrix;
    }
};