https://www.acmicpc.net/problem/1026

보물.java

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int []A = new int[N];
        int []B = new int[N];
        int S=0;
        for(int i=0; i<N; i++)
            A[i] = sc.nextInt();
        for(int i=0; i<N; i++)
            B[i] = sc.nextInt();
        sc.close();
        Arrays.sort(A);
        Arrays.sort(B);
        for(int i=0; i<N; i++)
            S += A[i]*B[N-i-1];
        System.out.print(S);
    }
}