My Java 8 Solution

public static String gridChallenge(List<String> grid) {
        for (int i = 0; i < grid.size(); i++) {
            char[] ca = grid.get(i).toCharArray();
            Arrays.sort(ca);
            grid.set(i, String.valueOf(ca));
        }
        
        for (int j = 0; j < grid.get(0).length(); j++) {
            for (int i = 1; i < grid.size(); i++) {
                if (grid.get(i).charAt(j) < grid.get(i - 1).charAt(j)) return "NO";
            }
        }
        
        return "YES";
    }

No clever way of solving this; You have to iterate through the list, convert each string into a char array, sort them, create a new sorted gridand than iterate through the new grid with a nested for loop, and and check if the vertical lines are in order.

The answers for some of the hidden test cases are literally wrong according to the definition presented in the problem

static string gridChallenge(List grid) { for (int i = 0; i < grid.Count; i++) { char[] caracteres = grid[i].ToCharArray();

    for (int j = 0; j < caracteres.Length - 1; j++)
    {
        for (int k = 0; k < caracteres.Length - 1 - j; k++)
        {
            if (caracteres[k] > caracteres[k + 1])
            {
                char temp = caracteres[k];
                caracteres[k] = caracteres[k + 1];
                caracteres[k + 1] = temp;
            }
        }
    }

    grid[i] = new string(caracteres);
}

for (int i = 0; i < grid.Count - 1; i++)
{
    for (int j = 0; j < grid[i].Length; j++)
    {
        if (grid[i][j] > grid[i + 1][j])
        {
            return "NO";
        }
    }
}

return "YES";

}

This question is garbage in its current state. The test cases do not conform to the requirements in the problem description, and the input parameters themselves contradict eachother.