Prime Arrangements.rs

// Runtime: 0 ms (Top 100.0%) | Memory: 2.20 MB (Top 44.44%)

const MOD: i64 = 1_000_000_007;
const PRIME: [i32; 25] = [
    2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97,
];

impl Solution {
    pub fn num_prime_arrangements(n: i32) -> i32 {
        let factorial_mod = |n: i32| -> i64 { (2..=n as i64).fold(1, |acc, x| (acc * x) % MOD) };
        let num_primes = PRIME.iter().take_while(|&&x| x <= n).count() as i32;
        ((factorial_mod(num_primes) * factorial_mod(n - num_primes)) % MOD) as i32
    }
}