695. Max Area of Island

问题描述

Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.

Find the maximum area of an island in the given 2D array. (If there is no island, the maximum area is 0.)

思路

类似 200. Number of Islands
用dfs的思路
一个一个过，已经经过的点变成0
recur

class Solution:
    def getIsland(self, grid, i, j, row, col, area):
        if i < 0 or i >= row or j < 0 or j >= col or grid[i][j] ==0:
            return area
        grid[i][j] = 0
        area += 1
        area = self.getIsland(grid, i + 1, j, row, col, area)
        area = self.getIsland(grid, i - 1, j, row, col, area)
        area = self.getIsland(grid, i, j + 1, row, col, area)
        area = self.getIsland(grid, i, j - 1, row, col, area)
        return area

    def maxAreaOfIsland(self, grid):
        """
        :type grid: List[List[int]]
        :rtype: int
        """
        if not grid or len(grid) == 0:
            return 0
        row = len(grid)
        col = len(grid[0])
        area = 0
        for i in range(row):
            for j in range(col):
                if grid[i][j] == 1:
                    tmp = self.getIsland (grid, i, j, row, col, 0)
                    area = max(tmp, area)

        return area