A_Desorting.cpp

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef pair<int, int> pi;
typedef unordered_map<ll, ll> mpp;
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define fr(i, a, b) for (int i = a; i < b; i++)
#define get(a)        \
    for (auto &i : a) \
    cin >> i
void wushangclan()
{
    int n;
    cin >> n;
    vl v(n);
    get(v);
    ll ans=INT_MAX;
    fr(i, 1, n)
    {
        if (v[i - 1] > v[i])
        {
            cout << 0 << endl;
            return;
        }
        ans=min(ans,((v[i]-v[i-1])/2LL+1LL));
    }
    cout<<ans<<endl;
}
int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        wushangclan();
    }
    return 0;
}