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This approach traverses the matrix in a spiral order by systematically altering the direction when encountering the boundary or an already filled space. Start with the initial direction as 'right'. Change direction to 'down', 'left', 'up' as necessary when a boundary or an already filled cell is encountered.
1#include <vector>
2
3struct ListNode {
4 int val;
5 ListNode *next;
6 ListNode(int x) : val(x), next(nullptr) {}
7};
8
9std::vector<std::vector<int>> spiralMatrix(int m, int n, ListNode* head) {
10 std::vector<std::vector<int>> matrix(m, std::vector<int>(n, -1));
11 int dirs[4][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
12 int dir_idx = 0;
13 int r = 0, c = 0;
14
15 for (int i = 0; head && i < m * n; ++i) {
16 matrix[r][c] = head->val;
17 head = head->next;
18
19 int nr = r + dirs[dir_idx][0], nc = c + dirs[dir_idx][1];
20
21 if (nr < 0 || nr >= m || nc < 0 || nc >= n || matrix[nr][nc] != -1) {
22 dir_idx = (dir_idx + 1) % 4;
23 nr = r + dirs[dir_idx][0];
24 nc = c + dirs[dir_idx][1];
25 }
26 r = nr;
27 c = nc;
28 }
29 return matrix;
30}
31
32// Example Usage
33int main() {
34 ListNode* head = new ListNode(3);
35 head->next = new ListNode(0);
36 head->next->next = new ListNode(2);
37 std::vector<std::vector<int>> result = spiralMatrix(3, 5, head);
38
39 for (const auto& row : result) {
40 for (int x : row) {
41 std::cout << x << " ";
42 }
43 std::cout << std::endl;
44 }
45
46 return 0;
47}
48The C++ solution for generating a spiral matrix starts by creating an m x n matrix initialized to -1. We navigate the matrix using four possible directions: right, down, left, and up, changing to the next one upon hitting matrix boundaries or previously visited cells. The solution ensures correct traversal using a direction index to rotate among the directions, effectively filling the matrix according to the smart direction transitions while connected to the linked list traversal.
In this approach, we fill the matrix in a spiral order by completing one 'layer' of the spiral at a time. Start filling from the outer layer to the inner layers progressively until the entire matrix is filled. Each layer comprises four segments: top row, right column, bottom row, and left column.
1#include <stdio.h>
2#include
In C, this approach dynamically allocates a 2D array initialized to -1, representing the m x n matrix. The algorithm uses boundary pointers (top, bottom, left, right) dynamically shifting them inward based on filled cells from the linked list. It rotates through the spiral pattern filling each side of the current layer at a time, ensuring every cell is processed appropriately in relation to the remaining linked list values.