1859. 백만 장자 프로젝트

package oSWExpertAcademy;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

//백만 장자 프로젝트 
public class D2_01 {
    public static void main(String[]args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
            //반복횟수 
            int count =  Integer.parseInt(br.readLine());
            for(int i=1; i<=count; i++) {
                //거래횟수  
                int    trade = Integer.parseInt(br.readLine());
                //거래횟수에 따른 가격 갯수 배열 
                int[] price = new int[trade];
                StringTokenizer st = new StringTokenizer(br.readLine());
                //총 이익 
                long benefit = 0;
                for(int j=0; j<trade; j++) {
                    price[j] = Integer.parseInt(st.nextToken());
                }
                int last = price[trade-1];
                for(int k=trade-2; k>=0; k--) {
                    if(price[k] > last) {
                        last = price[k];
                    }else {
                        benefit += last - price[k];
                    }
                }
                System.out.println("#"+i+" "+benefit);
            }
        } catch (NumberFormatException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}