Grid Challenge HackerRank Solution

GridChallenge.java

public static String gridChallenge(List<String> grid) {
        List<String> sortedStrings = new ArrayList();
        int n = grid.size();
        int m = grid.get(0).length();
        for(int i=0;i<grid.size();i++){
            String s = grid.get(i);
            char charArr[] = s.toCharArray();
            Arrays.sort(charArr);
            sortedStrings.add(new String(charArr));
            System.out.println(new String(charArr));
        }
        //Check columnwise sorting
        for(int i=1;i<n;i++){
            for(int j=0;j<m;j++){
                if( sortedStrings.get(i-1).charAt(j) > sortedStrings.get(i).charAt(j) )       return "NO";
            }
        }
        return "YES";
    }