[백준] BOJ - 11501 주식 java 자바 (실버2)

https://www.acmicpc.net/problem/11501

11501번: 주식

 

나의풀이

import java.util.*;
import java.io.*;
public class Main {
    public static void main(String args[]) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st = new StringTokenizer(br.readLine());
        
        int t= Integer.parseInt(st.nextToken());
        
        for(int i=0; i<t ; i++){
            st = new StringTokenizer(br.readLine());
            int n= Integer.parseInt(st.nextToken());
            int[] arr = new int[n];
            long answer= 0;
            
            st = new StringTokenizer(br.readLine());
            for(int j=0; j<n; j++){
                arr[j]= Integer.parseInt(st.nextToken());
            }
            
            int max=0;
            for(int k=n-1 ; k>=0; k--){
                if(max < arr[k]){
                    max= arr[k];
                }else{
                    answer += (max - arr[k]);
                }
            }
            
            bw.write(Long.toString(answer)+"\n");
            
        }
    
        bw.flush();
        br.close();
        bw.close();
        
    }
}