fourkind.py

from collections import defaultdict

from collections import defaultdict

n = 8
k = 4
good = 0;

for x in xrange(10**n - 1):
	s = str(x).zfill(8);
	a = defaultdict(int)
	for c in list(s):
		a[c] += 1;
	if k in a.values():
		good += 1;

print float(good)/float(10**n)