LeetCode 695 Max Area of Island - Algorithm

Your DFS function now returns an integer instead of void. Here's the approach:

$1.$ Loop through every cell. When you find an unvisited land cell, call DFS on it.

$2.$ In DFS, if the cell is out of bounds or water, return $0$.

$3.$ Mark the current cell as visited by setting it to $0$.

$4.$ Return $1$ (current cell) plus the DFS results from all $4$ neighbors.

$5.$ In the main loop, compare each DFS result to your running maximum.

The recursion builds area bottom-up. Leaf cells return $1$. Parent calls sum these up, giving you the total island size.