57. Max Area of Island

class Solution:
    def maxAreaOfIsland(self, grid: List[List[int]]) -> int:
        m, n = len(grid), len(grid[0])
        def area(r, c):
            if r < 0 or c < 0 or r >= m or c >= n or grid[r][c] != 1:
                return 0
            grid[r][c] = 0                     # mark visited
            return 1 + area(r + 1, c) + area(r - 1, c) + area(r, c + 1) + area(r, c - 1)
        return max(area(r, c) for r in range(m) for c in range(n))

class Solution {
    public int maxAreaOfIsland(int[][] grid) {
        int best = 0;
        for (int r = 0; r < grid.length; r++)
            for (int c = 0; c < grid[0].length; c++) best = Math.max(best, area(grid, r, c));
        return best;
    }
    private int area(int[][] g, int r, int c) {
        if (r < 0 || c < 0 || r >= g.length || c >= g[0].length || g[r][c] != 1) return 0;
        g[r][c] = 0;
        return 1 + area(g, r + 1, c) + area(g, r - 1, c) + area(g, r, c + 1) + area(g, r, c - 1);
    }
}

class Solution {
    int area(vector<vector<int>>& g, int r, int c) {
        if (r < 0 || c < 0 || r >= (int)g.size() || c >= (int)g[0].size() || g[r][c] != 1) return 0;
        g[r][c] = 0;
        return 1 + area(g, r + 1, c) + area(g, r - 1, c) + area(g, r, c + 1) + area(g, r, c - 1);
    }
public:
    int maxAreaOfIsland(vector<vector<int>>& grid) {
        int best = 0;
        for (int r = 0; r < (int)grid.size(); r++)
            for (int c = 0; c < (int)grid[0].size(); c++) best = max(best, area(grid, r, c));
        return best;
    }
};

function maxAreaOfIsland(grid) {
  const m = grid.length, n = grid[0].length;
  const area = (r, c) => {
    if (r < 0 || c < 0 || r >= m || c >= n || grid[r][c] !== 1) return 0;
    grid[r][c] = 0;
    return 1 + area(r + 1, c) + area(r - 1, c) + area(r, c + 1) + area(r, c - 1);
  };
  let best = 0;
  for (let r = 0; r < m; r++) for (let c = 0; c < n; c++) best = Math.max(best, area(r, c));
  return best;
}