1859. 백만 장자 프로젝트 자바

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

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        int TC = Integer.parseInt(bf.readLine().trim());
        for(int T=1;T<=TC;T++) {
            StringTokenizer st = new StringTokenizer(bf.readLine());
            int N = Integer.parseInt(st.nextToken());
            int[] arr = new int[N];
            st= new StringTokenizer(bf.readLine());
            for(int i=0;i<N;i++) {
                arr[i]=Integer.parseInt(st.nextToken());
            }
            int max = 0;
            long answer = 0;
            for(int i=arr.length-1;i>=0;i--) {
                if(max < arr[i]) {
                    max = arr[i];
                }else {
                    answer += max-arr[i];
                }
            }
            System.out.println("#"+T+" "+answer);
            }
        }
}