#include <bits/stdc++.h>
using namespace std;
int T, n, a[30005], b[30005];
long long sum[2];
int main() {
  scanf("%d", &T);
  while (T--) {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
    a[n + 1] = 0;
    for (int i = 1; i <= n + 1; i++) b[i] = a[i] - a[i - 1];
    sum[0] = sum[1] = 0;
    for (int i = 2; i <= n; i++) {
      if (b[i] > 0)
        sum[0] += b[i];
      else
        sum[1] -= b[i];
    }
    if (b[1] >= sum[1] && -b[n + 1] >= sum[0]) {
      printf("YES\n");
    } else
      printf("NO\n");
  }
  return 0;
}
