结合他人题解以及自己瞎琢磨得到的一些理解，有错误还请指正，谢谢！！

#include "bits/stdc++.h"

using namespace std;

typedef long long LL;

const int N = 3e5 + 10;

int t, n;
LL s[N], a[N]; // s为前缀和数组 a为存放前缀和顺序的数组
bool st[N];

int main()
{
    cin >> t;
    while (t--)
    {
        cin >> n;
        memset(st, 0, sizeof st);
        for (int i = 1; i <= n; i++)
            cin >> s[i], s[i] += s[i - 1];
        LL s0 = s[0], sn = s[n];
        if (s0 > sn)
            swap(s0, sn);
        sort(s, s + n + 1);
        // 寻找排完序后s0和sn的位置
        // 如果s0和sn相同的话则前面的为s0 后面的为sn
        for (int i = 0; i <= n; i++)
            if (s[i] == s0)
            {
                s0 = i;
                break;
            }
        for (int i = n; i >= 0; i--)
            if (s[i] == sn)
            {
                sn = i;
                break;
            }
        int l = 0, r = n;
        for (int i = s0; i >= 0; i -= 2)
        {
            a[l++] = s[i];
            st[i] = 1;
        }
        for (int i = sn; i <= n; i += 2)
        {
            a[r--] = s[i];
            st[i] = 1;
        }
        for (int i = 0; i <= n; i++)
            if (!st[i])
                a[l++] = s[i];
        LL res = 0;
        for (int i = 1; i <= n; i++)
            res = max(res, abs(a[i] - a[i - 1]));
        cout << res << endl;
    }
    return 0;
}