A31 - Divisors

提出

TLE

code: python

n = int(input())

three = 0

five = 0

threefive = 0

for i in range(1, n+1):

if i % 3 == 0:

three += 1

if i % 5 == 0:

five += 1

if i % 15 == 0:

threefive += 1

print(three + five - threefive)

解答

code: python

n = int(input())

a1 = (n // 3) # 3 で割り切れるものの個数

a2 = (n // 5) # 5 で割り切れるものの個数

a3 = (n // 15) # 3, 5 両方で割り切れるもの（= 15 の倍数）の個数

print(a1 + a2 - a3)