It is simple, When numbers all are zero click enter, so any one light will glow that row or column is correct number.
Example, When all number are zero, then clicked enter no light will glow so all numbers are incorrect then changed all to one and enters. When First Row first light and second column fight light will glow. So That column any of three is correct and first row ant of three is correct. So that will hold and remaining all changed to two. and noticed light will glow or not.