Enclosed Lakes Count

Problem

Count connected regions of zeros that are fully surrounded by ones.

grid is a rectangular list of rows holding only 0 and 1, and connectivity is 4-directional. A zero-region counts as a lake only when none of its cells sits on the grid border. Flood fill each unvisited region and track whether the border is touched.

Hint

A region touching any border cell drains away, so only strictly interior zero regions are lakes.

Test cases

case 1

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

expected: 1

case 2

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

expected: 0

case 3

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

expected: 1

case 4

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

expected: 2

Starter codePython

def count_enclosed_lakes(grid):
    # Your code here
    pass

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