11501번

11501

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
	int t;
	cin >> t;
	for (int i = 0; i < t; i++) {
		int num;
		vector<int> v;
		cin >> num;
		vector<int> result(num, 0);

		for (int j = 0; j < num; j++) {
			int tmp;
			cin >> tmp;
			v.push_back(tmp);
		}

		int maxNum = v[num - 1];

		for (int j = num - 2; j >= 0; j--) {
			if (maxNum <= v[j]) {
				maxNum = max(maxNum, v[j]);
			}
			result[j] = maxNum;
		}

		long long answer = 0;
		for (int j = 0; j < result.size(); j++) {
			if (result[j] != 0) {
				answer += (result[j] - v[j]);
			}
			}
		cout << answer << endl;
	}
}