[TASK] Day 4 + performance improvements

src/util.rs

@@ -3,16 +3,14 @@ use std::fmt::Display;
 
 use num::Integer;
 
-pub fn read_file(filename: &str) -> Vec<String> {
+pub fn read_file(filename: &str) -> String {
 
-    let contents = fs::read_to_string(filename)
+    return fs::read_to_string(filename)
         .expect("Couldn't read file!");
+}
 
-    let mut res: Vec<String> = Vec::new();
-    contents.lines().for_each(|l| res.push(String::from(l)));
-
-    res
-
+pub fn into_lines(input: String) -> Vec<String> {
+    return input.lines().map(|l| l.to_owned()).collect();
 }