Project Euler Problem 1 Solution

Project Euler Problem 1 Solution

Multiples of 3 and 5

by {BetaProjects} | Project Euler & HackerRank
Difficulty: Easy

Project Euler Problem 1 Statement

A positive fraction whose numerator is less than its denominator is called a proper fraction.
For any denominator, $d$, there will be $d - 1$ proper fractions; for example, with $d = 12$:
$1 / 12, 2 / 12, 3 / 12, 4 / 12, 5 / 12, 6 / 12, 7 / 12, 8 / 12, 9 / 12, 10 / 12, 11 / 12$.

We shall call a fraction that cannot be cancelled down a resilient fraction.
Furthermore we shall define the resilience of a denominator, $R(d)$, to be the ratio of its proper fractions that are resilient; for example, $R(12) = 4/11$.
In fact, $d = 12$ is the smallest denominator having a resilience $R(d) \lt 4/10$.

Find the smallest denominator $d$, having a resilience $R(d) \lt 15499/94744$.

Solution

Python Source Code

from sympy import totient

# Your primorial calculation
x = 2**3 * 3 * 5 * 7 * 11 * 13 * 17 * 19 * 23

def r(val):
    return totient(val) / (val - 1)

print(f"Value: {x}")
print(f"Ratio: {r(x)}")