project euler problem 12

pe12.py

#project euler problem 12
#auther @iizukak

#素因数分解する関数(試し割り法)
def fact(n):
    ans = []
    sq = n ** 0.5
    i = 2
    while n != 1:
        if i > sq:
            ans.append(n)
            break
        if n % i == 0:
            ans.append(i)
            n = n / i
        else:
            i += 1
    return ans 

#素因数分解の結果をもとに約数の個数を計算する関数
def divcount(L):
    tmp = [1]
    for i in range(len(L) - 1):
        if L[i] == L[i + 1]:
            tmp[-1] += 1
        else:
            tmp.append(1)
    ans = 1
    for i in range(len(tmp)):
        ans = ans * (tmp[i] + 1)
    return ans

def pe12():
    for i in range(1, 2 ** 20):
        #using triangle number formula
        tri = int((i * (i + 1)) / 2)
        if (divcount(fact(tri))) > 501:
            return tri

print(pe12())