Question

排列公式的一组问题,PYTHON解决或者数学方法

Answer 1

start = 0

end = 10000

a = {4:0,3:0,2:0,1:0}

t = set()

for i in range(start,end):

t.clear()

[t.add(s) for s in '%04d' % i]

if len(t) == 1:

a[4] += 1

elif len(t) == 3:

a[2] += 1

elif len(t) == 4:

a[1] += 1

elif ('%04d' % i).count(t.pop()) != 2:

a[3] += 1

print a

# {1:5040,2:4320,3:360,4:10}