36. Valid Sudoku

LeetCode

2D Array, HashSet link

class Solution {
    public boolean isValidSudoku(char[][] board) {
        Set<String> check=new HashSet<>();
        for(int i=0;i<9;i++){
            for(int j=0;j<9;j++){
                char ch=board[i][j];
                if(ch!='.'){
                    if(!check.add(ch+"in row"+i)||
                       !check.add(ch+"in colum"+j)||
                       !check.add(ch+"in box"+i/3+"-"+j/3)
                       ){
                          return false; 
                       }
                }
            }
        }
        return true;
    }
}