[08_revisit_everything] automate solution of challenges one through seven

src/lib/challenges/c2_these_numbers_are_big.rs

@@ -0,0 +1,23 @@
+use std::sync::LazyLock;
+use std::str::FromStr;
+use rug::Integer;
+use rug::integer::Order;
+use sha2::{Sha256, Digest};
+
+static M: LazyLock<Integer> = LazyLock::new(|| Integer::from_str("14004392365098131090160062970945115111185775413941111064876648140973294115502980816410773368597517292734034227298996122159833675150497554142801209096513652073059992938078366061434391648276904643753267405058183481162693381822800709938988762923").unwrap());
+static E: LazyLock<Integer> = LazyLock::new(|| Integer::from(65537));
+
+pub fn solve(name: &str) -> (u64, Integer) {
+    let mut x = sha256(name);
+    x += 4;
+    for _ in 0..10_000 {
+        for _ in 0..100 {
+            x.pow_mod_mut(&E, &M).unwrap();
+        }
+    }
+    (20_000, x)
+}
+
+pub fn sha256(name: &str) -> Integer {
+    Integer::from_digits(Sha256::digest(name).as_slice(), Order::MsfBe)
+}