Part 1 complete

day_01/src/main.rs

@@ -1,7 +1,7 @@
+use std::env;
 use std::error::Error;
 use std::fs::File;
-use std::io::{self, BufReader, prelude::*};
+use std::io::{BufReader, prelude::*};
-use std::{env, fs};
 
 fn parse_line(line: &str) -> Result<(i64, i64), Box<dyn Error>> {
     // Split line on whitespace
@@ -18,6 +18,23 @@ fn parse_line(line: &str) -> Result<(i64, i64), Box<dyn Error>> {
     return Ok((first_element, second_element));
 }
 
+/// Part one of day 1
+/// Calculate the difference after sorting each list from smallest to biggest
+fn calculate_diff(mut left_list: Vec<i64>, mut right_list: Vec<i64>) -> i64 {
+    // sort lists
+    left_list.sort();
+    right_list.sort();
+
+    let mut accumulator = 0;
+    for (index, left_value) in left_list.iter().enumerate() {
+        let right_value = right_list[index];
+        let absolute_diff = (left_value - right_value).abs();
+        accumulator += absolute_diff;
+    }
+
+    accumulator
+}
+
 fn main() -> Result<(), Box<dyn Error>> {
     // Handle command input
     let args: Vec<String> = env::args().collect();
@@ -32,11 +49,18 @@ fn main() -> Result<(), Box<dyn Error>> {
     let input_file = File::open(input_file_string)?;
     let input_reader = BufReader::new(input_file);
 
-    for (index, line) in input_reader.lines().enumerate() {
+    let mut left_list: Vec<i64> = Vec::new();
+    let mut right_list: Vec<i64> = Vec::new();
+
+    for line in input_reader.lines() {
         let line = line?;
         let parsed_line = parse_line(&line)?;
-        println!("({},{})", parsed_line.0, parsed_line.1);
+        //println!("({},{})", parsed_line.0, parsed_line.1);
+        left_list.push(parsed_line.0);
+        right_list.push(parsed_line.1);
     }
 
+    println!("Result: {}", calculate_diff(left_list, right_list));
+
     return Ok(());
 }