#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#define LL long long
#define pb push_back
using namespace std;
const int N = 100010;
int a[N], t[N];
bool del[5];

int main() {
    int T;
    scanf("%d", &T);
    while (T--) {
        int n;
        scanf("%d", &n);
        for (int i = 1; i <= n; ++i) {
            scanf("%d", &a[i]);
            if (i > 1) t[i - 2] = abs(a[i] - a[i - 1]);
        }
        sort(t, t + n - 1, greater<int>());
        if (n == 3) t[2] = 0;
        LL ans = 0, maxx;
        for (int i = 1; i <= n; ++i) {
            del[0] = del[1] = del[2] = 0;
            if (i > 1) {
                for (int j = 0; j < 3; ++j)
                    if (!del[j] && abs(a[i] - a[i - 1]) == t[j]) {
                        del[j] = 1; break;
                    }
            }
            if (i < n) {
                for (int j = 0; j < 3; ++j)
                    if (!del[j] && abs(a[i + 1] - a[i]) == t[j]) {
                        del[j] = 1; break;
                    }
            }
            if (i > 1 && i < n)
                maxx = abs(a[i + 1] - a[i - 1]);
            else
                maxx = 0;
            for (int j = 0; j < 3; ++j)
                if (!del[j])
                    maxx = max(maxx, (LL)t[j]);
            ans += maxx;
        }
        printf("%I64d\n", ans);
    }
    return 0;
}