Data commit

Task/Prime-decomposition/Rust/prime-decomposition.rust

@@ -0,0 +1,92 @@
+use num_bigint::BigUint;
+use num_traits::{One, Zero};
+use std::fmt::{Display, Formatter};
+
+#[derive(Clone, Debug)]
+pub struct Factors {
+    pub number: BigUint,
+    pub result: Vec<BigUint>,
+}
+
+impl Factors {
+    pub fn of(number: BigUint) -> Factors {
+        let mut factors = Self {
+            number: number.clone(),
+            result: Vec::new(),
+        };
+
+        let big_2 = BigUint::from(2u8);
+        let big_4 = BigUint::from(4u8);
+
+        factors.check(&big_2);
+        factors.check(&BigUint::from(3u8));
+
+        let mut divisor = BigUint::from(5u8);
+        while &divisor * &divisor <= factors.number {
+            factors.check(&divisor);
+            divisor += &big_2;
+            factors.check(&divisor);
+            divisor += &big_4;
+        }
+
+        if factors.number > BigUint::one() {
+            factors.result.push(factors.number);
+        }
+
+        factors.number = number; // Restore the number
+        factors
+    }
+
+    pub fn is_prime(&self) -> bool {
+        self.result.len() == 1
+    }
+
+    fn check(&mut self, divisor: &BigUint) {
+        while (&self.number % divisor).is_zero() {
+            self.result.push(divisor.clone());
+            self.number /= divisor;
+        }
+    }
+}
+
+impl Display for Factors {
+    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+        let mut iter = self.result.iter();
+
+        match iter.next() {
+            None => write!(f, "[]"),
+
+            Some(first) => {
+                write!(f, "[{}", first)?;
+                for next in iter {
+                    write!(f, ", {}", next)?;
+                }
+
+                write!(f, "]")
+            }
+        }
+    }
+}
+
+fn print_factors(number: BigUint) {
+    let factors = Factors::of(number);
+
+    if factors.is_prime() {
+        println!("{} -> {} (prime)", factors.number, factors);
+    } else {
+        println!("{} -> {}", factors.number, factors);
+    }
+}
+
+fn main() {
+    print_factors(24u32.into());
+    print_factors(32u32.into());
+    print_factors(37u32.into());
+
+    // Find Mersenne primes
+
+    for n in 2..70 {
+        print!("2**{} - 1: ", n);
+        print_factors((BigUint::from(2u8) << n) - BigUint::one());
+    }
+}