So is this checkers or sudoku?

How would I do that

pseudocode

for(i=0;i<9;i++){ //row

maybe an arraylist of horizontals

for(j=0;j<9;j++){ // columns

//check for distinct row value

if(the arraylist of horizontals does not contain something?)

System.out.println("no distinct num")

what happened when you tried it? Does it solve the problem?

Are the first 9 in the top row? Second 9 in the second row? last 9 end up in the last row? If all 3 are yes then it seems right so far.

Looks to me like the only thing you are missing is the confidence to move forward.