PERMUT1 - Permutations


Let A = [a1, a2, ... an] be a permutation of integers 1, 2, ... n. A pair of indices (i, j), 1 <= i <= j <= n, is an inversion of the permutation A if ai > aj. We are given integers n > 0 and k >= 0. What is the number of n-element permutations containing exactly k inversions?

For instance, the number of 4-element permutations with exactly 1 inversion equals 3.

Task

Write a program which for each data set from a sequence of several data sets:

  • reads integers n and k from input,
  • computes the number of n-element permutations with exactly k inversions,
  • writes the result to output.

Input

The first line of the input file contains one integer d, 1 <= d <= 10, which is the number of data sets. The data sets follow. Each data set occupies one line of the input file and contains two integers n (1 <= n <= 12) and k (0 <= k <= 98) separated by a single space.

Output

The i-th line of the output file should contain one integer - the number of n-element permutations with exactly k inversions.

Example

Input:
1
4 1

Output:
3

hide comments
shubham gupta: 2013-08-10 07:02:13

can anyone please explain why p<n*(n+1)/2
it should be p<(n)*(n-1)/2
for example if n=3 maximum inversions would be 2 [3 2 1].
correct me if i am wrong...

Aayush Bahuguna: 2012-09-29 22:18:13

A simple dp problem :)

npsabari: 2012-07-20 08:46:01

DP makes it look easy!

sudhanshu barthwal: 2012-03-16 03:21:42

can anyone please post some test cases..

Prakhar Jain: 2011-12-24 10:11:27

nice one.....:)

Gaston Ingaramo: 2011-07-20 20:04:09

Hey ~neo~ the inversions are
2,1,3,4
1,3,2,4 and
1,2,4,3

~neo~: 2011-07-19 09:59:19

can anyone explain above test case.??

Nanda Bagus Pradnyana: 2011-01-16 07:26:04

cant anyone let me show any test case?


Added by:adrian
Date:2004-06-22
Time limit:3s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All
Resource:III Polish Collegiate Team Programming Contest (AMPPZ), 1998