Method isValid

Java/valid-sudoku.java:20–29

(ArrayList<Integer> arr)

*/
class Solution {
    public boolean isValid(ArrayList<Integer> arr){
        int[] fre = new int[10];
        for(int ele : arr){
            fre[ele]++;
            if(fre[ele] > 1){
                return false;
            }
        }
        return true;
    }
    public boolean isValidSudoku(char[][] board) {
        for(int i=0; i<9; i++){
            ArrayList<Integer> row = new ArrayList<>();