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  1. pub fn is_prime(n: u64) -> bool {
  2.     // Handle edge cases first
  3.     if n <= 1 {
  4.         return false;
  5.     }
  6.     // Special case for 2 (the only even prime)
  7.     if n == 2 {
  8.         return true;
  9.     }
  10.     // Eliminate even numbers > 2
  11.     if n % 2 == 0 {
  12.         return false;
  13.     }
  14.  
  15.     // Check divisors up to sqrt(n)
  16.     let sqrt_n = (n as f64).sqrt() as u64 + 1;
  17.     for i in (3..sqrt_n).step_by(2) {
  18.         if n % i == 0 {
  19.             return false;
  20.         }
  21.     }
  22.     true
  23. }
  24.  
  25. fn main() {
  26.     let numbers = [2, 15, 23, 49, 1_000_000_007];
  27.  
  28.     for &n in &numbers {
  29.         println!("{} is {}a prime", n, if is_prime(n) { "" } else { "not " });
  30.     }
  31. }
Success #stdin #stdout 0.01s 5288KB
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Standard input is empty
stdout
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2 is a prime
15 is not a prime
23 is a prime
49 is not a prime
1000000007 is a prime
https://ideone.com/sVBGNv
language:
Rust (rust 1.56)
created:
13 days ago
visibility:
public

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