complete 5369.rs 11689.rs 15649.rs

storage/zeta/rs/completed/11689.rs

@@ -0,0 +1,65 @@
+use std::io::stdin;
+
+fn get_primes_up_to(n: u64) -> Vec<u64> {
+    let mut i = 3;
+    let mut primes = vec![2];
+    while i <= n {
+        let mut is_prime = true;
+        for &p in &primes {
+            if p * p > i {
+                break;
+            }
+            if i % p == 0 {
+                is_prime = false;
+                break;
+            }
+        }
+        if is_prime {
+            primes.push(i);
+        }
+        i += 2;
+    }
+
+    primes
+}
+
+fn get_divisors(n: u64) -> Vec<(u64, u64)> {
+    let primes = get_primes_up_to((n as f64).sqrt() as u64 + 1);
+    let mut divisors = vec![];
+    let mut remainder = n;
+
+    for &p in &primes {
+        if p * p > remainder {
+            break;
+        }
+        let mut count = 0;
+        while remainder % p == 0 {
+            remainder /= p;
+            count += 1;
+        }
+        if count > 0 {
+            divisors.push((p, count));
+        }
+    }
+
+    if remainder > 1 {
+        divisors.push((remainder, 1));
+    }
+    divisors
+}
+
+fn euler_phi(n: u64) -> u64 {
+    let divisors = get_divisors(n);
+    let mut result = n;
+    for (p, _) in divisors {
+        result = result / p * (p - 1);
+    }
+    result
+}
+
+fn main() {
+    let mut line = String::new();
+    stdin().read_line(&mut line).unwrap();
+    let n: u64 = line.trim().parse().unwrap();
+    println!("{}", euler_phi(n));
+}