feat(problem): 2 - even fibonacci numbers

src/bin/1.rs

@@ -1,7 +1,9 @@
-// Problem 1 - Multiples of 3 or 5
+/*
+Problem 1 - Multiples of 3 or 5
 
-// If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23. 
-// Find the sum of all the multiples of 3 or 5 below 1000. 
+If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
+Find the sum of all the multiples of 3 or 5 below 1000.
+*/
 
 use std::collections::HashSet;
 

src/bin/2.rs

@@ -0,0 +1,28 @@
+/*
+Problem 2 - Even Fibonacci numbers
+
+Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
+1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
+By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
+*/
+
+fn fibonacci(upper_bound: usize) -> Vec<usize> {
+	// F_0 = 1, F_1 = 2
+	let mut sequence = vec![1, 2];
+
+	// F_n = F_(n - 1) + F_(n - 2)
+	while sequence[sequence.len() - 1] < upper_bound {
+		let new_value = sequence[sequence.len() - 1] + sequence[sequence.len() - 2];
+		sequence.push(new_value);
+	}
+
+	return sequence;
+}
+
+fn main() {
+	let sequence = fibonacci(4000000);
+	let even = sequence.iter().filter(|n| *n % 2 == 0);
+	let sum: usize = even.sum();
+
+	print!("The sum of the first 4000000 even fibonacci numbers is {}", sum);
+}

src/main.rs

@@ -74,29 +74,39 @@ async fn new() -> Result<(), Box<dyn std::error::Error>> {
         .collect::<Vec<&str>>()
         .join("");
 
-    let mut problem = re.replace_all(
-        Box::leak(
-            document
-                .select(&content_selector)
-                .next()
-                .unwrap()
-                .inner_html()
-                .into_boxed_str()
-        ), 
-        " "
-    ).to_string();
+    let mut problem = re
+        .replace_all(
+            Box::leak(
+                document
+                    .select(&content_selector)
+                    .next()
+                    .unwrap()
+                    .inner_html()
+                    .into_boxed_str()
+            ), 
+            " "
+        )
+        .to_string()
+        .replace("$$", " ");
 
     let file_body = format!(
-        "// Problem {} - {}
+        "/*
+Problem {} - {}
 
-//{}
+{}
+*/
 
 fn main() {{
     println!(\"Hello World!\");  
 }}", 
         problem_number,
         html_escape::decode_html_entities(&mut title).to_string(),
-        html_escape::decode_html_entities(&mut problem).split("\n").filter(|s| s != &"").collect::<Vec<&str>>().join("\n//")
+        html_escape::decode_html_entities(&mut problem)
+            .split("\n")
+            .map(|s| s.trim())
+            .filter(|s| s != &"")
+            .collect::<Vec<&str>>()
+            .join("\n")
     );
 
     // Create the file