Count Non-Zero Pixels

Problem

Count the number of non-zero pixels in a 2D image.

An empty image has 0 non-zero pixels.

case 1

in: [[[0,1,0],[2,0,3]]]

expected: 3

case 2

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

expected: 0

case 3

in: [[[1,2],[3,4]]]

expected: 4

case 4

in: [[]]

expected: 0

Starter codePython

def count_nonzero(image):
    # Your code here
    pass

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