unsorted containing indices of all rows except the last one, since we compare each row with the next one.res to 0, which will hold the count of columns to delete.j.i in unsorted such that strs[i][j] > strs[i+1][j].res as we need to delete this column.unsorted by removing indices where strs[i][j] < strs[i+1][j] as these rows are sorted with respect to the current column.res as the minimum number of columns to delete.