2658.py

class Solution(object):
    def findMaxFish(self, grid):
        """
        :type grid: List[List[int]]
        :rtype: int
        """
        directions = [[0,1], [0,-1], [1,0], [-1,0]]
        m = len(grid)
        n = len(grid[0])
        maxFish = 0

        def dfs(i, j, m, n):
            fish = 0
            
            if grid[i][j] == 0:
                return fish
            
            fish += grid[i][j]
            grid[i][j] = -1  # Visited

            for dir in directions:
                nr = i + dir[0]
                nc = j + dir[1]
                if 0 <= nr < m and 0 <= nc < n:
                    if grid[nr][nc] > 0:
                        fish += dfs(nr, nc, m, n)
            
            return fish

        for i in xrange(m):
            for j in xrange(n):
                if grid[i][j] == 0:
                    continue
                maxFish = max(maxFish, dfs(i, j, m, n))

        return maxFish