9.1.7 | Checkerboard V2 Answers

Actually, without offset but with (r + c) % 2 :

Row 0 (r=0): #_#_#_#_ (where _ is space) Row 1 (r=1): _#_#_#_# Row 2: #_#_#_#_ Row 3: _#_#_#_# 9.1.7 checkerboard v2 answers

Example of incorrect pattern (no offset): Actually, without offset but with (r + c)