$($Method $2)$ Now, let's implement a better method:

$$ Similarly, take the scores of n students as input, sort them, and then

divide them into k groups.

$$ Again, assume that lower group numbers correspond to higher scores.

$$ It would be ideal if the scores of students within each group were

similar.

$$ Therefore, calculate the variance of student scores in each group, and

aim to minimize the sum of these variances across all groups.

$$ However, each group must have at least one student, and the variance

of a group with only one student is considered to be $0.$

Write it in Java code