MARBLES  Marbles
Hänschen dreams he is in a shop with an infinite amount of marbles. He is allowed to select n marbles. There are marbles of k different colors. From each color there are also infinitely many marbles. Hänschen wants to have at least one marble of each color, but still there are a lot of possibilities for his selection. In his effort to make a decision he wakes up. Now he asks you how many possibilites for his selection he would have had. Assume that marbles of equal color can't be distinguished, and the order of the marbles is irrelevant.
Input
The first line of input contains a number T <= 100 that indicates the number of test cases to follow. Each test case consists of one line containing n and k, where n is the number of marbles Hänschen selects and k is the number of different colors of the marbles. You can assume that 1<=k<=n<=1000000.
Output
For each test case print the number of possibilities that Hänschen would have had. You can assume that this number fits into a signed 64 bit integer.
Example
Input: 2 10 10 30 7 Output: 1 475020
hide comments
Pranay Kumar:
20160124 12:09:07
Easy problem if you are into maths! Got AC in 1 go... 

try2catch:
20160115 15:53:02
stars and bars 

CounterNormalize:
20160114 19:24:10
TLE in python by just using factorial. 2 WA's in C++ due to improper nCr function.


mukesh227194:
20151122 22:13:27
my 100th one!!!!!


irbis9:
20151109 14:47:03
The key is to find the number of ways of selecting k items out of n items such that order doesn't matter and repetition is allowed. 

nonushikhar:
20151024 12:00:14
silly mistakes got me 2wa !!!!!! otherwise very easy prob 

dragonemperor:
20151019 13:51:38
Bars and stars. AC at first go 

farmers_rice:
20151009 02:34:44
keep getting NZEC error even though the only exceptions thrown are in input/output 

Sarthak Munshi:
20151006 17:54:01
STARS AND BARS ! 

xproxmess:
20150927 19:57:49
This is my code  http://ideone.com/UfKbDT

Added by:  Adrian Kuegel 
Date:  20040619 
Time limit:  0.248s 
Source limit:  10000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: NODEJS PERL 6 VB.net 
Resource:  own problem 