def gridChallenge(grid):
    sorted_grid = ["".join(sorted(row)) for row in grid]
    num_cols = len(sorted_grid[0])
    num_rows = len(sorted_grid)
    
    for col_idx in range(num_cols):
        columns = []
        for row_idx in range(num_rows):
            columns.append(sorted_grid[row_idx][col_idx])
       
        if columns != sorted(columns):
            return "NO"
    return "YES"

    public static String gridChallenge(List<String> grid) {
        for (int i=0; i < grid.size(); i++) {
            String element = grid.get(i);
            String sortedEl = Stream.of(element.split(""))
                    .sorted().collect(Collectors.joining());
            grid.set(i, sortedEl);
        }
        
        boolean sorted = true;
        for (int j=0; j < grid.get(0).length(); j++) {
            List<String> myList = new ArrayList<>();
            for (int k=0; k < grid.size(); k++) {
                myList.add(grid.get(k).substring(j, j+1));
            }
            String original = String.join("", myList);
            Collections.sort(myList);
            String sortedStr = String.join("", myList);
            sorted = !original.equals(sortedStr) ? false : sorted;
        }
        return sorted ? "YES" : "NO";
    }