(c++) SWEA "1859) 백만 장자 프로젝트"

https://swexpertacademy.com/main/code/problem/problemDetail.do?contestProbId=AV5LrsUaDxcDFAXc 

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#include <iostream>
#include <vector>
using namespace std;

int main() {
	int T; cin >> T;
	for (int i = 1; i <= T; i++) {
		cout << "#" << i << " ";
		int N; cin >> N;
		vector<int> list;
		long long sum = 0;
		for (int k = 0; k < N; k++) {
			int n; cin >> n;
			list.push_back(n);
		}
		int max = list[list.size() - 1];
		for (int k = list.size() - 2; k >= 0;k--) {
			if (list[k] < max) {
				sum += (long long)(max - list[k]);
			}
			else {
				max = list[k];
			}
		}
		cout << sum << endl;
	}
	return 0;
}