Zigzag Index

Problem

Return the position (0 to 63) of the cell (row, col) in the standard 8x8 JPEG zigzag order, which starts (0,0), (0,1), (1,0), (2,0), (1,1), (0,2), ... Rows and columns are 0-indexed. Return -1 for out-of-range input.

Hint

The scan alternates between up-right and down-left diagonals.

Test cases

case 1

in: [0,0]

expected: 0

case 2

in: [0,1]

expected: 1

case 3

in: [1,0]

expected: 2

case 4

in: [1,1]

expected: 4

case 5

in: [7,7]

expected: 63

Starter codePython

def zigzag_index(row, col):
    # Your code here
    pass

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