LeetCode 6111. Spiral matrix IV

LeetCode 6111. Spiral matrix IV

Writing spiral matrix with offset method

/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode() : val(0), next(nullptr) {} * ListNode(int x) : val(x), next(nullptr) {} * ListNode(int x, ListNode *next) : val(x), next(next) {} * }; */
class Solution {
    
public:
    int dx[4] = {
    -1, 0, 1, 0}, dy[4] = {
    0, 1, 0, -1};

    vector<vector<int>> spiralMatrix(int n, int m, ListNode* head) {
    
        vector<vector<int>> res(n, vector<int>(m, -1));
        int x = 0, y = 0, d = 1;
        for(int i = 0; i < n * m && head; i ++)
        {
    
            res[x][y] = head -> val;
            int a = a + dx[d], b = b + dy[d];
            if(a < 0 || a >= n || b < 0 || b >= m || res[a][b] != -1)
            {
    
                d = (d + 1) % 4;
                a = x + dx[d], b = y + dy[d];
            }
            x = a, y = b;
            head = head -> next;
        }
        return res;
    }
};