Nonzero AC Count

Problem

Count the nonzero entries of a block excluding the DC term at (0, 0). This is the number of (run, value) symbols a JPEG-style encoder must emit for the alternating-current coefficients.

Hint

Quantization usually drives most AC coefficients to zero.

Test cases

case 1

in: [[[5,1,0],[0,2,0],[0,0,3]]]

expected: 3

case 2

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

expected: 0

case 3

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

expected: 0

case 4

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

expected: 3

Starter codePython

def nonzero_ac_count(block):
    # Your code here
    pass

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