Facebook Hacker Cup 2011 Round 1A - Wine Tasting

wineTasting.py

#!/usr/bin/python
import sys

def fac(n):
    '''n!'''
    if n==0 or n==1:
        return 1
    else:
        return n*fac(n-1)

def facFrac(n,k):
    '''n!/k!'''
    res = 1
    for i in range(k+1,n+1):
        res *= i
    return res

def choose(n,k):
    return facFrac(n,k)/fac(n-k)

def M(n):
    res = 0
    for i in range(2,n+1):
        if i % 2:
            res -= facFrac(n,i)
        else:
            res += facFrac(n,i)
    return res

def rightArrange(n,k):
    total = fac(n)
#    print total
    for i in range(k):
        total -= choose(n,i)*M(n-i)   
#        print n,i,M(n-i),total
    return total



infile = sys.argv[1]
f = open(infile)

N = int(f.readline().strip())

for i in range(N):
    n, k = map(int,f.readline().strip().split(' '))
    print rightArrange(n,k) % 1051962371

f.close()