class Solution {
    public boolean checkValid(int[][] matrix) {
        int n=matrix.length;
        Set<Integer> set1 = new HashSet<>();
        Set<Integer> set2 = new HashSet<>();
        for(int i=0; i<n; i++){ 
            for(int j=0; j<n; j++){ 
                if(!set1.add(matrix[i][j]) || !set2.add(matrix[j][i])) return false;
            }
            set1 = new HashSet<>();
            set2 = new HashSet<>();
        }
        return true;
    }
}