2326. Spiral Matrix IV

You are given two integers m and n, which represent the dimensions of a matrix.

You are also given the head of a linked list of integers.

Generate an m x n matrix that contains the integers in the linked list presented in spiral order (clockwise), starting from the top-left of the matrix. If there are remaining empty spaces, fill them with -1.

Return the generated matrix.

/**
 * 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:
    vector<vector<int>> spiralMatrix(int n, int m, ListNode* head) {
        vector<vector<int>> res(n, vector<int>(m, -1));
        int dy[4]{-1,0,1,0}, dx[4]{0,1,0,-1}, d = 1;
        int y = 0, x = 0;
        while(head) {
            res[y][x] = head->val;
            head = head->next;
            for(int i = 0; i < 4; i++) {
                int ny = y + dy[(d + i) % 4], nx = x + dx[(d + i) % 4];
                if(0 <= ny and ny < n and 0 <= nx and nx < m and res[ny][nx] == -1) {
                    y = ny, x = nx, d = (d + i) % 4;
                    break;
                }
            }
        }
        return res;
    }
};