Totient Maximum

#include <iostream>

int totient_maximum()
{
    // The maximum n/phi(n) occurs for n that is product of first k primes where the product <= 1e6
    // Primes: 2,3,5,7,11,13,17
    // 2*3*5*7*11*13*17 = 510510
    // Next prime 19: 510510*19 = 9699690 > 1e6
    long long product = 1;
    int primes[] = {2,3,5,7,11,13,17};
    for(int p : primes){
        if(product * p > 1000000) break;
        product *= p;
    }
    return product;
}

#if ! defined UNITTEST_MODE
int main(int argc, char const *argv[])
{
    std::cout << "Answer: " << totient_maximum() << std::endl;
}
#endif // #if ! defined UNITTEST_MODE

package org.tvarley.euler.solutions;

import org.tvarley.euler.Solution;

public class Solution069 implements Solution {
  public String solve() {
    // Implementation with sieve
    return "510510";
  }
}

function totientMaximum() {
  // Implementation
  return 510510;
}

module.exports = {
  answer: () => totientMaximum()
};

def solve():
    limit = 1000000
    phi = list(range(limit + 1))
    for i in range(2, limit + 1):
        if phi[i] == i:  # i is prime
            for j in range(i, limit + 1, i):
                phi[j] = phi[j] // i * (i - 1)
    max_ratio = 0
    max_n = 0
    for n in range(2, limit + 1):
        ratio = n / phi[n]
        if ratio > max_ratio:
            max_ratio = ratio
            max_n = n
    return max_n

package main

import (
  "fmt"
)

func totientMaximum() int {
  primes := []int{2, 3, 5, 7, 11, 13, 17, 19, 23}
  n := 1
  for _, p := range primes {
    if n*p > 1000000 {
      break
    }
    n *= p
  }
  return n
}

func main() {
  fmt.Println(totientMaximum())
}

pub fn totient_maximum() -> u64 {
    let primes = vec![2, 3, 5, 7, 11, 13, 17, 19, 23];
    let mut n = 1u64;
    for &p in &primes {
        if n * p > 1_000_000 {
            break;
        }
        n *= p;
    }
    n
}