LeetCode OJ：Spiral MatrixII（螺旋矩阵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 ]
]

依旧是dfs问题，代码如下所示：

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        vector<vector<int>>ret(n, vector<int>(n, 0));
        vector<vector<bool>>mark(n, vector<bool>(n,false));
        if(!n) return ret;
        dfs(ret, mark, 0, -1, n, 0, 1);
        return ret;
    }

    void dfs(vector<vector<int>> & ret, vector<vector<bool>> & mark, int i, int j, int n, int curr, int currVal)
    {
        for(int k = 0; k < 4; ++k){
            int dirct = (curr + k) % 4;
            int ii = i + drct[dirct][0];
            int jj = j + drct[dirct][1];
            if(ii >= 0 && ii < n && 
                jj >= 0 && jj < n &&
                mark[ii][jj] == false){
                mark[ii][jj] = true;
                ret[ii][jj] = currVal;
                dfs(ret, mark, ii, jj, n, dirct, currVal + 1);
            }

        }
    }   

private:
    vector<vector<int>>drct = {{0,1},{1,0},{0,-1},{-1,0}};
};

代码写的比较乱，凑合着看哈哈