D：沒想到這個看起來簡單的題能卡我這麼久。

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef pair<LL,int> pii;
const int N = 2e5+5;
const int M = 1e6+5;
const LL Mod = 998244353;
#define pi acos(-1)
#define INF 1e18
#define CT0 cin.tie(0),cout.tie(0)
#define IO ios::sync_with_stdio(false)
#define
 
 dbg(ax) cout << "now this num is " << ax << endl;
namespace FASTIO{
    inline LL read(){
        LL x = 0,f = 1;char c = getchar();
        while(c < '0' || c > '9'){if(c == '-') f = -1;c = getchar();}
        while(c >= '0' && c <= '9'){x = (x<<1)+(x<<3
 
)+(c^48);c = getchar();}
        return x*f;
    }
}
using namespace FASTIO;

int a[N];
int main()
{
    int ca;ca = read();
    while(ca--)
    {
        int n;n = read();
        for(int i = 1;i <= n;++i) a[i] = read();
        int f = 0,used = 0,pre = a[1];
        for(int i = 1;i <= n;++i){
            a[i] 
 
-= used;
            if(a[i] < 0){f = 1;break;}
            if(a[i] > pre) used += a[i] - pre;
            pre = min(pre,a[i]);
        }
        printf("%s\n",f ? "NO" : "YES");
    }
    system("pause");
    return 0;
}