Interview Street Challenges - Direct conn

Direct_conn.java

package interviewstreet;

import java.util.Scanner;

public class Direct_conn {

	int num;
	int[] distance;
	int[] population;
	
	public Direct_conn(int num, int[] distance, int[] population) {
		this.num = num;
		this.distance = distance;
		this.population = population;
	}

	public static void main(String args[])
	{
		Scanner scanner = new Scanner(System.in);
		 int no_cases = scanner.nextInt();
			for (int i = 0; i < no_cases; i++) {
				int num_of_cities = scanner.nextInt();
				int dist[]=new int[num_of_cities];
				int pop[]=new int[num_of_cities];
				Direct_conn dc=new Direct_conn(num_of_cities-1,dist,pop);
				for(int j=0;j<num_of_cities;j++)
				{
					dist[j]=scanner.nextInt();
				}
				for(int k=0;k<num_of_cities;k++)
				{
					pop[k]=scanner.nextInt();
				}
				System.out.println(dc.solve());
			}
	}

	private long solve() {
		long ret=0;
		for(int i=0;i<num;i++)
		{
			for(int j=i;j<num;j++)
			{
				ret+=perform(i,j+1);
			}
		}
		return ret%1000000007;
	}

	private long perform(int i, int j) {
		int conn=Math.max(population[i],population[j]);
		int dist=distance[j]-distance[i];
		long ret=conn*dist;
		return ret;
	}
}