#include <bits/stdc++.h>
using namespace std;

void solve() {
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    vector<int> inv;
    for (int i = 0; i < n - 1; i++) {
        if (a[i] > a[i + 1]) {
            inv.push_back(i);
        }
    }

    if (inv.empty()) {
        cout << "YES\n";
        return;
    }

    long long L = 0;
    for (int i : inv) {
        L = max(L, (long long)a[i] - a[i + 1]);
    }

    long long R = 2e18; 
    for (size_t i = 0; i < inv.size() - 1; i++) {
        int left = inv[i] + 1;
        int right = inv[i + 1];
        
        long long mx_diff = -1;
        for (int j = left; j < right; j++) {
            mx_diff = max(mx_diff, (long long)a[j + 1] - a[j]);
        }
        
        if (mx_diff == -1) {
            R = -1;
            break;
        }
        R = min(R, mx_diff);
    }

    if (R != -1 && L <= R) {
        cout << "YES\n";
    } else {
        cout << "NO\n";
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}