LeetCode: Max Area Of Island Solution

1var maxAreaOfIsland = function (grid) {
2  const [m, n] = [grid.length, grid[0].length]
3  const visited = Array.from({ length: m }, _ => Array(n).fill(false))
4
5  const valid = (row, col) => {
6    return (
7      row >= 0 &&
8      row < m &&
9      col >= 0 &&
10      col < n &&
11      !visited[row][col] &&
12      grid[row][col] !== 0
13    )
14  }
15
16  const traverse = (row, col) => {
17    if (!valid(row, col)) {
18      return 0
19    }
20
21    visited[row][col] = true
22
23    return (
24      1 +
25      traverse(row, col + 1) +
26      traverse(row, col - 1) +
27      traverse(row + 1, col) +
28      traverse(row - 1, col)
29    )
30  }
31
32  let res = 0
33  for (let row = 0; row < m; row++) {
34    for (let col = 0; col < n; col++) {
35      res = Math.max(res, traverse(row, col))
36    }
37  }
38
39  return res
40}