[数学] leetcode 885 Spiral Matrix III

problem:https://leetcode.com/problems/spiral-matrix-iii/

       这道题挺简单的，只需要模拟一下题意就可以了。不断地增加步数和改变方向，直到已经读取到矩阵的所有数据。

class Solution {
public:
    vector<int> dx{ 0,1,0,-1 };
    vector<int> dy{ 1,0,-1,0 };
    vector<vector<int>> spiralMatrixIII(int R, int C, int r0, int c0) {
        vector<vector<int>> res;
        int N = R * C;
        int step = 1;
        bool bUpdateStep = false;
        int k = 0;
        int times = 0;
        while (res.size() < N)
        {
            if(r0 >= 0 && r0 < R && c0 >= 0 && c0 < C)
                res.push_back({ r0, c0 });

            r0 += dx[k];
            c0 += dy[k];
            times++;
            if (times == step)
            {
                times = 0;
                k = (k + 1) % 4;
                if (k % 2 == 0)
                {
                    step++;
                }
            }
        }
        return res;
    }
};