/***************************************************
* Author  : Anav Prasad
* Handle  : vrangr
* Created : Fri Sep 20 20:31:58 IST 2024
****************************************************/
#include <bits/stdc++.h>

#define debug(...) (void)42
#ifdef LOCAL
    #undef debug
    #include <algo/debug.hpp>
    const bool DEBUG = true;
#else
    [[maybe_unused]] const bool DEBUG = false;
#endif

using namespace std;

typedef unsigned int uint;
typedef long long int ll;
typedef unsigned long long int ull;
typedef long double ld;
typedef __int128_t i128;
#define endl "\n"
#define fastIO ios_base::sync_with_stdio(false),cin.tie(0)
#define TEST int T;cin>>T;while(T--)solve();
#define TEST1 solve();
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(v) ((int)(v).size())
#define GET_MACRO(_1,_2,_3,_4,NAME,...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, forsn, debug, forn)(__VA_ARGS__)
#define forn(i, n) for (__typeof(n) i = 0; i < n; i++)
#define forsn(i, st, end, d) for(__typeof(end) i = st; (d>0?i<=end:i>=end); i+=((__typeof(end))d))
template<typename type>inline void print_vec(const vector<type> &v){rep(i,sz(v))cout<<v[i]<<" \n"[i==sz(v)-1];}
void solve();
#ifndef ATCODER_INTERNAL_BITOP_HPP
#define ATCODER_INTERNAL_BITOP_HPP 1

#ifdef _MSC_VER
#include <intrin.h>
#endif

namespace atcoder {

namespace internal {

// @param n `0 <= n`
// @return minimum non-negative `x` s.t. `n <= 2**x`
int ceil_pow2(int n) {
    int x = 0;
    while ((1U << x) < (unsigned int)(n)) x++;
    return x;
}

// @param n `1 <= n`
// @return minimum non-negative `x` s.t. `(n & (1 << x)) != 0`
int bsf(unsigned int n) {
#ifdef _MSC_VER
    unsigned long index;
    _BitScanForward(&index, n);
    return index;
#else
    return __builtin_ctz(n);
#endif
}

}  // namespace internal

}  // namespace atcoder

#endif  // ATCODER_INTERNAL_BITOP_HPP

#ifndef ATCODER_LAZYSEGTREE_HPP
#define ATCODER_LAZYSEGTREE_HPP 1

#include <algorithm>
#include <cassert>
#include <iostream>
#include <vector>
namespace atcoder {

template <class S,
          S (*op)(S, S),
          S (*e)(),
          class F,
          S (*mapping)(F, S),
          F (*composition)(F, F),
          F (*id)()>
struct lazy_segtree {
  public:
    lazy_segtree() : lazy_segtree(0) {}
    lazy_segtree(int n) : lazy_segtree(std::vector<S>(n, e())) {}
    lazy_segtree(const std::vector<S>& v) : _n(int(v.size())) {
        log = internal::ceil_pow2(_n);
        size = 1 << log;
        d = std::vector<S>(2 * size, e());
        lz = std::vector<F>(size, id());
        for (int i = 0; i < _n; i++) d[size + i] = v[i];
        for (int i = size - 1; i >= 1; i--) {
            update(i);
        }
    }

    void set(int p, S x) {
        assert(0 <= p && p < _n);
        p += size;
        for (int i = log; i >= 1; i--) push(p >> i);
        d[p] = x;
        for (int i = 1; i <= log; i++) update(p >> i);
    }

    S get(int p) {
        assert(0 <= p && p < _n);
        p += size;
        for (int i = log; i >= 1; i--) push(p >> i);
        return d[p];
    }

    S prod(int l, int r) {
        assert(0 <= l && l <= r && r <= _n);
        if (l == r) return e();

        l += size;
        r += size;

        for (int i = log; i >= 1; i--) {
            if (((l >> i) << i) != l) push(l >> i);
            if (((r >> i) << i) != r) push(r >> i);
        }

        S sml = e(), smr = e();
        while (l < r) {
            if (l & 1) sml = op(sml, d[l++]);
            if (r & 1) smr = op(d[--r], smr);
            l >>= 1;
            r >>= 1;
        }

        return op(sml, smr);
    }

    S all_prod() { return d[1]; }

    void apply(int p, F f) {
        assert(0 <= p && p < _n);
        p += size;
        for (int i = log; i >= 1; i--) push(p >> i);
        d[p] = mapping(f, d[p]);
        for (int i = 1; i <= log; i++) update(p >> i);
    }
    void apply(int l, int r, F f) {
        assert(0 <= l && l <= r && r <= _n);
        if (l == r) return;

        l += size;
        r += size;

        for (int i = log; i >= 1; i--) {
            if (((l >> i) << i) != l) push(l >> i);
            if (((r >> i) << i) != r) push((r - 1) >> i);
        }

        {
            int l2 = l, r2 = r;
            while (l < r) {
                if (l & 1) all_apply(l++, f);
                if (r & 1) all_apply(--r, f);
                l >>= 1;
                r >>= 1;
            }
            l = l2;
            r = r2;
        }

        for (int i = 1; i <= log; i++) {
            if (((l >> i) << i) != l) update(l >> i);
            if (((r >> i) << i) != r) update((r - 1) >> i);
        }
    }

    template <bool (*g)(S)> int max_right(int l) {
        return max_right(l, [](S x) { return g(x); });
    }
    template <class G> int max_right(int l, G g) {
        assert(0 <= l && l <= _n);
        assert(g(e()));
        if (l == _n) return _n;
        l += size;
        for (int i = log; i >= 1; i--) push(l >> i);
        S sm = e();
        do {
            while (l % 2 == 0) l >>= 1;
            if (!g(op(sm, d[l]))) {
                while (l < size) {
                    push(l);
                    l = (2 * l);
                    if (g(op(sm, d[l]))) {
                        sm = op(sm, d[l]);
                        l++;
                    }
                }
                return l - size;
            }
            sm = op(sm, d[l]);
            l++;
        } while ((l & -l) != l);
        return _n;
    }

    template <bool (*g)(S)> int min_left(int r) {
        return min_left(r, [](S x) { return g(x); });
    }
    template <class G> int min_left(int r, G g) {
        assert(0 <= r && r <= _n);
        assert(g(e()));
        if (r == 0) return 0;
        r += size;
        for (int i = log; i >= 1; i--) push((r - 1) >> i);
        S sm = e();
        do {
            r--;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!g(op(d[r], sm))) {
                while (r < size) {
                    push(r);
                    r = (2 * r + 1);
                    if (g(op(d[r], sm))) {
                        sm = op(d[r], sm);
                        r--;
                    }
                }
                return r + 1 - size;
            }
            sm = op(d[r], sm);
        } while ((r & -r) != r);
        return 0;
    }

  private:
    int _n, size, log;
    std::vector<S> d;
    std::vector<F> lz;

    void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
    void all_apply(int k, F f) {
        d[k] = mapping(f, d[k]);
        if (k < size) lz[k] = composition(f, lz[k]);
    }
    void push(int k) {
        all_apply(2 * k, lz[k]);
        all_apply(2 * k + 1, lz[k]);
        lz[k] = id();
    }
};

}  // namespace atcoder

#endif  // ATCODER_LAZYSEGTREE_HPP

int main() {
    fastIO;
    TEST;
#ifdef LOCAL
    cout << "\nTime elapsed: " << (double)clock() / CLOCKS_PER_SEC << " s.\n";
#endif
    return 0;
}

class S {
public:
    ll val;
    S() : val(0ll) {}
    S(ll v) : val(v) {}
};

S op(S a, S b) {
    return S(a.val+b.val);
}

S e() {
    return S();
}

class F {
public:
    ll val;
    F() : val(LLONG_MIN){}
    F(ll v) : val(v){}
};

S mapping(F f, S x) {
    if (f.val == LLONG_MIN) return x;
    return S(f.val);
}

F composition(F f, F g) {
    if (f.val == LLONG_MIN) return g;
    if (g.val == LLONG_MIN) return f;
    return f;
}

F id() {
    return F();
}

void solve() {
    ll n; cin >> n;
    vector<ll> a(n);
    rep(i,n) cin >> a[i];
    vector<S> vec(n);
    atcoder::lazy_segtree<S, op, e, F, mapping, composition, id> seg(vec);
    rep(i,n) {
        if (i == 0 || seg.get(i-1).val <= a[i]) {
            seg.apply(i,F(a[i]));
            continue;
        }
        ll low = 0ll, high = i-1ll;
        while(low < high) {
            ll mid = (low+high)/2ll;
            ll sum = seg.prod(mid,i).val;
            if ((sum+a[i])/(i-mid+1ll) <= seg.get(mid).val)
                high = mid;
            else low = mid+1ll;
        }
        assert(high < i);
        ll sum = (seg.prod(high,i).val + a[i]), ct = i-high+1ll;
        ll rem = sum%ct, avg = sum/ct;
        seg.apply(high,high+ct-rem,F(avg));
        if (rem) seg.apply(high+ct-rem,i+1ll,F(avg+1ll));
        if (high) assert(seg.get(high-1ll).val <= seg.get(high).val);
    }
    cout << seg.get(n-1ll).val - seg.get(0ll).val << endl;
}