8VC Venture Cup 2016 - Elimination Round
F
Group Projects
Codeforces
2400
原题
← EG →
翻译中…

There are $*n*$ students in a class working on group projects. The students will divide into groups (some students may be in groups alone), work on their independent pieces, and then discuss the results together. It takes the $*i*$-th student $*a*_{*i*}$ minutes to finish his/her independent piece.

翻译中…

If students work at different paces, it can be frustrating for the faster students and stressful for the slower ones. In particular, the imbalance of a group is defined as the maximum $*a*_{*i*}$ in the group minus the minimum $*a*_{*i*}$ in the group. Note that a group containing a single student has an imbalance of $0$. How many ways are there for the students to divide into groups so that the total imbalance of all groups is at most $*k*$?

翻译中…

Two divisions are considered distinct if there exists a pair of students who work in the same group in one division but different groups in the other.

翻译中…

Input

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The first line contains two space-separated integers $*n*$ and $*k*$ ($1 ≤ *n* ≤ 200$, $0 ≤ *k* ≤ 1000$) — the number of students and the maximum total imbalance allowed, respectively.

翻译中…

The second line contains $*n*$ space-separated integers $*a*_{*i*}$ ($1 ≤ *a*_{*i*} ≤ 500$) — the time it takes the $*i*$-th student to complete his/her independent piece of work.

翻译中…

Output

翻译中…

Print a single integer, the number of ways the students can form groups. As the answer may be large, print its value modulo $10^{9} + 7$.

翻译中…

Note

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In the first sample, we have three options:

翻译中…
  • The first and second students form a group, and the third student forms a group. Total imbalance is $2 + 0 = 2$.
  • The first student forms a group, and the second and third students form a group. Total imbalance is $0 + 1 = 1$.
  • All three students form their own groups. Total imbalance is $0$.
翻译中…

In the third sample, the total imbalance must be $0$, so each student must work individually.

翻译中…

样例

Input #1
3 2
2 4 5
Output #1
3
InputCopy OutputCopy
Input #2
4 3
7 8 9 10
Output #2
13
InputCopy OutputCopy
Input #3
4 0
5 10 20 21
Output #3
1
InputCopy OutputCopy
题目信息
题号
626F
时间限制
2 s
内存限制
256 MB
标签
动态规划

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。