import java.util.*;
import java.io.*;
 
 class Ideone{
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int t = Integer.parseInt(br.readLine());
 
        while (t-- > 0) {
            int n = Integer.parseInt(br.readLine());
            String[] str = br.readLine().split(" ");
            int[] a = new int[n];
            for (int i = 0; i < n; i++) {
                a[i] = Integer.parseInt(str[i]);
            }
 
            // prefix min cost: making all elements before i equal to a[i]
            int[] left = new int[n];
            int minVal = a[0];
            for (int i = 1; i < n; i++) {
                left[i] = left[i - 1] + (a[i] - minVal);
                minVal = Math.min(minVal, a[i]);
            }
 
            // suffix min cost: making all elements after i equal to a[i]
            int[] right = new int[n];
            minVal = a[n - 1];
            for (int i = n - 2; i >= 0; i--) {
                right[i] = right[i + 1] + (a[i] - minVal);
                minVal = Math.min(minVal, a[i]);
            }
 
            int res = Integer.MAX_VALUE;
            for (int i = 0; i < n; i++) {
                res = Math.min(res, left[i] + right[i]);
            }
 
            System.out.println(res);
        }
    }
}

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