You are given a?0-indexed?2D matrix?grid?of size?m x n, where?(r, c)?represents:

• A?land?cell if?grid[r][c] = 0, or

• A?water?cell containing?grid[r][c]?fish, if?grid[r][c] > 0.

A fisher can start at any?water?cell?(r, c)?and can do the following operations any number of times:

• Catch all the fish at cell?(r, c), or

• Move to any adjacent?water?cell.

Return?the?maximum?number of fish the fisher can catch if he chooses his starting cell optimally, or?0?if no water cell exists.

An?adjacent?cell of the cell?(r, c), is one of the cells?(r, c + 1),?(r, c - 1),?(r + 1, c)?or?(r - 1, c)?if it exists.

?

Example 1:

Input: grid = [[0,2,1,0],[4,0,0,3],[1,0,0,4],[0,3,2,0]]

Output: 7

Explanation: The fisher can start at cell (1,3) and collect 3 fish, then move to cell (2,3)?and collect 4 fish.

Example 2:

Input: grid = [[1,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,1]]

Output: 1

Explanation: The fisher can start at cells (0,0) or (3,3) and collect a single fish.

?

Constraints:

• m == grid.length

• n == grid[i].length

• 1 <= m, n <= 10

• 0 <= grid[i][j] <= 10

DFS經(jīng)典題目；

我是一直沒(méi)做出來(lái)，因?yàn)橛玫撵o態(tài)變量。。。尷尬；

Runtime:?28 ms, faster than?12.44%?of?Java?online submissions for?Maximum Number of Fish in a Grid.

Memory Usage:?43.1 MB, less than?10.36%?of?Java?online submissions for?Maximum Number of Fish in a Grid.