CF1691D · Max GEQ Sum

• 难度：1800
• 标签：binary search、constructive algorithms、data structures、divide and conquer、implementation、two pointers
• 链接：https://codeforces.com/problemset/problem/1691/D
• 时间限制：1.5 seconds　内存限制：256 megabytes
• 出现位置：Day05-二分答案-ST表-RMQ/选做

中文题意

以下为官方英文题意（课堂讲解时请要求学生能用自己的话复述条件与目标）。

You are given an array $a$ of $n$ integers. You are asked to find out if the inequality $$\max(a_i, a_{i + 1}, \ldots, a_{j - 1}, a_{j}) \geq a_i + a_{i + 1} + \dots + a_{j - 1} + a_{j}$$ holds for all pairs of indices $(i, j)$, where $1 \leq i \leq j \leq n$.

Note（官方）： In test cases $1$ and $2$, the given condition is satisfied for all $(i, j)$ pairs. In test case $3$, the condition isn't satisfied for the pair $(1, 2)$ as $\max(2, 3) \lt 2 + 3$.

输入格式（中文）

Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 10^5$). Description of the test cases follows. The first line of each test case contains a single integer $n$ ($1 \leq n \leq 2 \cdot 10^5$)  — the size of the array. The next line of each test case contains $n$ integers $a_1, a_2, \ldots, a_n$ ($-10^9 \le a_i \le 10^9$). It is guaranteed that the sum of $n$ over all test cases does not exceed $2 \cdot 10^5$.

输出格式（中文）

For each test case, on a new line output "YES" if the condition is satisfied for the given array, and "NO" otherwise. You can print each letter in any case (upper or lower).

样例

样例 1

输入：

3
4
-1 1 -1 2
5
-1 2 -3 2 -1
3
2 3 -1

输出：

YES
YES
NO