#include <bits/stdc++.h>
using namespace std;
const int maxp = 22;
const long double EPS = 1e-18;
const long long INF = 2e18;
const int MOD = 1e9 + 7;
const int N = 2e5 + 1;
void yesno(bool a) {
  if (a) {
    cout << "YES" << '\n';
  } else {
    cout << "NO" << '\n';
  }
}
long long power(long long x, long long n, long long m) {
  if (n == 0) return 1;
  long long u = power(x, n / 2, m);
  u = (u * u) % m;
  if (n % 2) u = (u * x) % m;
  return u;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int i, arr[n];
    for (i = 0; i < n; i++) cin >> arr[i];
    int mx = 0;
    int mn = arr[0];
    bool ok = 1;
    for (i = 0; i < n; i++) {
      if (arr[i] < mx) {
        ok = 0;
        break;
      }
      int val = arr[i] - mx;
      mn = min(mn, val);
      arr[i] -= mn;
      mx = max(mx, arr[i]);
    }
    for (i = 0; i < n - 1; i++) {
      ok &= arr[i] <= arr[i + 1];
    }
    yesno(ok);
  }
}
