Codeforces Round 906 (Div. 1) |
---|

Finished |

Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

constructive algorithms

greedy

math

sortings

*1700

No tag edit access

The problem statement has recently been changed. View the changes.

×
B. Doremy's Connecting Plan

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputDoremy lives in a country consisting of $$$n$$$ cities numbered from $$$1$$$ to $$$n$$$, with $$$a_i$$$ people living in the $$$i$$$-th city. It can be modeled as an undirected graph with $$$n$$$ nodes.

Initially, there are no edges in the graph. Now Doremy wants to make the graph connected.

To do this, she can add an edge between $$$i$$$ and $$$j$$$ if

$$$$$$ \sum_{k \in S} a_k \ge i\cdot j \cdot c, $$$$$$

where $$$S$$$ is the set of all the nodes that are currently in the same connected component of either $$$i$$$ or $$$j$$$, and $$$c$$$ is a given constant.

Can Doremy make the graph connected?

Two nodes $$$(i, j)$$$ are in the same connected component if there exists a path from $$$i$$$ to $$$j$$$. A graph is connected if all its nodes are in the same connected component.

Input

The input consists of multiple test cases. The first line contains a single integer $$$t$$$ ($$$1\le t\le 10^4$$$) — the number of test cases. The description of the test cases follows.

The first line contains two integers $$$n$$$, $$$c$$$ ($$$2\le n\le 2\cdot 10^5$$$, $$$1 \le c \le 10^6$$$) — the number of nodes and the constant.

The second line of each test case contains $$$ n $$$ integers $$$ a_1,a_2,\ldots,a_n $$$ ($$$0 \le a_i \le 10^{12}$$$) — the number of people living in the $$$i$$$-th city.

It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2\cdot 10^5$$$.

Output

For each test case, print "YES" (without quotes), if it is possible to make the graph connected, and "NO" (without quotes) otherwise.

You can print letters in any case (upper or lower).

Example

Input

74 100 20 15 102 11 15 10 1 0 4 1995 21 1 3 1 15 55 6 1 10 25 10000001000000000000 1000000000000 1000000000000 1000000000000 10000000000003 10 0 2

Output

Yes Yes Yes No No Yes No

Note

In the first test case, Doremy can add edges in the following order:

- Add $$$(1,2)$$$. This operation is valid because $$$a_1 + a_2 = 20 \ge i\cdot j \cdot c = 20$$$.
- Add $$$(1,3)$$$. This operation is valid because $$$a_1 + a_2 + a_3 = 35 \ge i \cdot j \cdot c = 30$$$.
- Add $$$(1,4)$$$. This operation is valid because $$$a_1 + a_2 + a_3 + a_4 = 45 \ge i \cdot j \cdot c = 40$$$.

In the second test case, Doremy can add edge $$$(1,2)$$$ because $$$a_1 + a_2 =2 \ge 1 \cdot 2 \cdot 1$$$. After that, the graph is connected.

In the third test case, Doremy can add edges in the order $$$(5,4)$$$, $$$(5,3)$$$, $$$(5,2)$$$ and $$$(5,1)$$$.

In the fourth test case, Doremy cannot add any edge at all.

Codeforces (c) Copyright 2010-2023 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Dec/02/2023 06:04:03 (f1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|