https://school.programmers.co.kr/learn/courses/30/lessons/12941
import java.util.Arrays;
class Solution
{
public int solution(int []A, int []B)
{
int answer = 0;
int size = B.length;
Arrays.sort(A);
Arrays.sort(B);
for(int i = 0; i < A.length; i++){
answer += A[i] * B[size - (1 + i)];
}
return answer;
}
}