Largest Region Size

Problem

Find the size of the largest 4-connected region of ones in a binary grid.

grid is a rectangular list of rows holding only 0 and 1. Flood fill every unvisited land cell and keep the biggest region size seen. Return 0 when the grid contains no ones at all.

Hint

Mark cells when you push them so diagonally touching regions stay separate.

Test cases

case 1

in: [[[1,1,0],[1,0,1],[0,0,1]]]

expected: 3

case 2

in: [[[0,0],[0,0]]]

expected: 0

case 3

in: [[[1,1],[1,1]]]

expected: 4

case 4

in: [[[1,0,0,1]]]

expected: 1

case 5

in: [[[1]]]

expected: 1

Starter codePython

def largest_region_size(grid):
    # Your code here
    pass

5 test cases · run your code against them in the editor