生成螺旋数组，递归

题目：

点击打开链接

解答：

递归生成，先生成边界，后递归生成里面的矩阵。

代码：

class Solution {public:vector<vector<int> > generateMatrix(int n) {vector<vector<int> > res(n, vector<int>(n));if (n == 0)return res;print(0, n - 1, 1, res);return res;}private:void print(int a, int b, int n, vector<vector<int> > &res){//a b代表矩阵的边界if (a > b)return;int i;//生成上面一行for (i = a; i <= b; i++)res[a][i] = n++;//生成右边列for (i = a + 1; i <= b; i++)res[i][b] = n++;//生成下边行for (i = b - 1; i >= a; i--)res[b][i] = n++;//生成左边列for (i = b - 1; i > a; i--)res[i][a] = n++;print(a + 1, b - 1, n, res);}};