INV - Inversions
Calculate the number of ways that k things can be 'chosen' from a set of n things.
Input
The first line of input is the number of tests t <= 100000. Next t lines contains two integers each n and k, separated with a single space. 0 <= k <= n <= 100000.
Output
For each test output the number of ways that k things can be 'chosen' from a set of n things modulo 1000000007.
Example
Input: 3 9876 5432 100 50 100000 50000 Output: 266875274 538992043 149033233
hide comments
LE BEIER:
2012-09-04 07:39:53
can someone kindly explain to me is this problem about combination or is it about finding the inversion of the permutation? |
Added by: | Spooky |
Date: | 2009-04-13 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | ADA95 DOC ASM32 BASH BF C CSHARP CPP C99 CLPS LISP sbcl LISP clisp D FORTRAN HASK ICON ICK JAVA LUA NEM NICE OCAML PAS-GPC PAS-FPC PDF PERL PHP PIKE PS PRLG-swi PYTHON RUBY SCM guile SCM qobi ST TEXT WHITESPACE |