lab 01

labs/01/primes.rs

@@ -0,0 +1,50 @@
+use std::collections::HashMap;
+
+fn sieve(p: Vec<usize>, mut acc: Vec<usize>, n: usize) -> Vec<usize> {
+    if p.len() == 0 {
+        return acc;
+    }
+
+    let h = p[0];
+
+    if h * h > n {
+        acc.extend(p); // acc ++ [h | t] in Elixir impl
+        return acc;
+    }
+
+    acc.push(h);
+    let remaining = p
+        .into_iter()
+        .skip(1) //
+        .filter(|x| x % h != 0)
+        .collect();
+
+    sieve(remaining, acc, n)
+}
+
+fn primes(m: usize, n: usize) -> Vec<usize> {
+    let c = (2..=n).collect();
+    sieve(c, Vec::new(), n)
+        .into_iter()
+        .filter(|x| x > (&m))
+        .collect()
+}
+
+fn sort_prime(n: usize) -> String {
+    let mut digits: Vec<char> = n.to_string().chars().collect();
+    digits.sort();
+    digits.into_iter().collect()
+}
+
+fn main() {
+    let p = primes(100_000, 1_000_000);
+    println!("{}", p.len());
+
+    let mut groups: HashMap<String, Vec<usize>> = HashMap::new();
+    for x in p {
+        groups.entry(sort_prime(x)).or_default().push(x);
+    }
+
+    let largest = groups.values().max_by_key(|g| g.len()).unwrap();
+    println!("{}", largest.len());
+}