leetcode

0 // Matrix BFS/Flood fill Recursive

1

2 typedef vector<vector<int>> Matrix;

3 typedef vector<vector<bool>> Marked;

4 const vector<pair<int, int>> offsets = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};

5

6 int n, m;

7 int valid(int x, int y) { return x >= 0 && x < n && y >= 0 && y < m; }

8

9 bool dfs(const Matrix &mat, Marked &mark, int a, int b) {

10 mark[a][b] = true;

11 for (auto [oa, ob] : offsets) {

12 int x = a + oa, y = b + ob;

13 if (!valid(x, y) || mark[x][y]) continue;

14 if (dfs(mat, mark, x, y)) return true;

15 }

16 mark[a][b] = false;

17

18 return false;

19 }