Max Area of Island

# https://leetcode.com/problems/max-area-of-island/description/
# complex number make things simplers

class Solution(object):
    def maxAreaOfIsland(self, grid):
        """
        :type grid: List[List[int]]
        :rtype: int
        """
        grid = {i + j*1j: val for i, row in enumerate(grid) for j, val in enumerate(row)}
        def area(z):
            return grid.pop(z, 0) and 1 + sum(area(z + 1j**k) for k in range(4))
        return max(map(area, set(grid)))