#define _CRT_SECURE_NO_WARNINGS
#include<cstdio>
#include<iostream>
#include<vector>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<set>

/*______________#########____________________*\
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______#####______;###________###______#________
\*______##_______####________####____________*/

using namespace std;

long long abss(long long a)
{
    if (a < 0)
    {
        return -1 * a;
    }
    else
    {
        return a;
    }
}

int cmp(long long a, long long b)
{
    return a>b;
}

long long data[100005];
long long dats[100005];

int main()
{
    int T;
    scanf("%I64d", &T);
    while (T--)
    {
        long long ans = 0;
        long long n;
        memset(dats, 0, sizeof(dats));
        scanf("%I64d", &n);
        for (int i = 0; i < n; i++)
        {
            scanf("%I64d", &data[i]);
        }
        long long maxs = 0;
        for (int i = 1; i < n - 1; i++)
        {
            maxs = max(maxs, abss(data[i] - data[i + 1]));
        }
        ans += maxs;
        maxs = 0;
        for (int i = 0; i < n - 2; i++)
        {
            maxs = max(maxs, abss(data[i] - data[i + 1]));
        }
        ans += maxs;
        maxs = 0;

        for (int i = 0; i < n - 1; i++)
        {
            dats[i] = abss(data[i] - data[i + 1]);
        }
        sort(dats, dats + n - 1, cmp);
        long long t1, t2;
        for (int i = 1; i < n - 1; i++)
        {
            maxs = 0;
            t1 = min(abss(data[i] - data[i + 1]), abss(data[i - 1] - data[i]));
            t2 = max(abss(data[i] - data[i + 1]), abss(data[i - 1] - data[i]));
            if (t1 != dats[0] && t2!= dats[0])
            {
                ans += max(dats[0], abss(data[i - 1] - data[i + 1]));
            }
            else if (t1 != dats[1] && t2 != dats[1])
            {
                ans += max(dats[1], abss(data[i - 1] - data[i + 1]));
            }
            else
            {
                ans += max(dats[2], abss(data[i - 1] - data[i + 1]));
            }
        }
        printf("%I64d\n", ans);
    }
}