39

src/euler39/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "euler39"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+
+[profile.release]
+debug = true

src/euler39/src/lib.rs

@@ -0,0 +1,30 @@
+#[derive(Debug, Hash)]
+pub struct Triangle {
+    a: usize,
+    b: usize,
+    c: usize,
+}
+
+impl Triangle {
+    pub fn new(a: usize, b: usize, c: usize) -> Option<Self> {
+        Self { a, b, c }.sanity_check()
+    }
+
+    fn sanity_check(self) -> Option<Self> {
+        if !self.sides_are_sufficiently_long() {
+            return None;
+        }
+        if !self.pythagoras_holds() {
+            return None;
+        }
+        Some(self)
+    }
+
+    fn sides_are_sufficiently_long(&self) -> bool {
+        self.a + self.b > self.c || self.a + self.c > self.b || self.b + self.c > self.a
+    }
+
+    fn pythagoras_holds(&self) -> bool {
+        self.a.pow(2) + self.b.pow(2) == self.c.pow(2)
+    }
+}

src/euler39/src/main.rs

@@ -0,0 +1,29 @@
+use std::collections::HashMap;
+
+use euler39::Triangle;
+
+fn main() {
+    let mut vec = vec![];
+    for p in 2..=1_000_usize {
+        vec.push(0);
+        let current = vec.get_mut(p - 2).unwrap();
+        for a in 2..=p {
+            let remainder = p - a;
+            let limit = remainder / 2;
+            for b in 1..limit {
+                let c = remainder - b;
+                if let Some(_triangle) = Triangle::new(a, b, c) {
+                    *current += 1;
+                }
+            }
+        }
+    }
+
+    let result = vec
+        .iter()
+        .enumerate()
+        .max_by_key(|(_, value)| **value)
+        .unwrap();
+
+    println!("{}: {}", result.0 + 2, result.1)
+}