CodeForces #1285B Just Eat It [java]

import java.util.Scanner;

public class JustEatIt_1285B {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int t = scan.nextInt();
		long[] a;
		long pre = 0, po = 0;
		int n;

		for (int i = 0; i < t; i++) {
			n = scan.nextInt();
			a = new long[n];
			boolean yes = true;
			pre = 0;
			po = 0;
			for (int j = 0; j < n; j++) {
				a[j] = scan.nextLong();
				pre = pre + a[j];
				if (pre <= 0) {
					yes = false;
				}
			}
			for (int j = n - 1; j > 0; j--) {
				po = po + a[j];
				if (po <= 0) {
					yes = false;
				}
			}
			if (yes == true)
				System.out.println("YES");
			else
				System.out.println("NO");
		}
		scan.close();
	}
}

prefix 사용