solve day 1 part 2

src/bin/01.rs

@@ -1,9 +1,10 @@
+use adv_code_2024::*;
 use anyhow::*;
-use std::fs::File;
-use std::io::{BufRead, BufReader};
 use code_timing_macros::time_snippet;
 use const_format::concatcp;
-use adv_code_2024::*;
+use itertools::Itertools;
+use std::fs::File;
+use std::io::{BufRead, BufReader};
 
 const DAY: &str = "01";
 const INPUT_FILE: &str = concatcp!("input/", DAY, ".txt");
@@ -23,6 +24,22 @@ fn main() -> Result<()> {
     //region Part 1
     println!("=== Part 1 ===");
 
+    fn read_challenge<R: BufRead>(reader: R) -> (Vec<i32>, Vec<i32>) {
+        let mut left: Vec<i32> = Vec::new();
+        let mut right: Vec<i32> = Vec::new();
+
+        for line in reader.lines() {
+            let line = line.unwrap();
+
+            let mut iter = line.split_whitespace();
+            left.push(iter.next().unwrap().parse::<i32>().unwrap());
+            right.push(iter.next().unwrap().parse::<i32>().unwrap());
+        }
+        assert_eq!(left.len(), right.len());
+
+        (left, right)
+    }
+
     fn pop_minimum(list: &mut Vec<i32>) -> i32 {
         let mut min_index: usize = 0;
         let mut minimum: &i32 = list.first().unwrap();
@@ -36,26 +53,13 @@ fn main() -> Result<()> {
     }
 
     fn part1<R: BufRead>(reader: R) -> Result<usize> {
-
-        let mut left: Vec<i32> = Vec::new();
-        let mut right: Vec<i32> = Vec::new();
-
-        for line in reader.lines() {
-            let line = line?;
-
-            let mut iter = line.split_whitespace();
-            left.push(iter.next().unwrap().parse::<i32>()?);
-            right.push(iter.next().unwrap().parse::<i32>()?);
-        }
-
-        assert_eq!(left.len(), right.len());
-
+        let (mut left, mut right) = read_challenge(reader);
         let mut distance = 0;
-        
+
         while !left.is_empty() {
             let left_min = pop_minimum(&mut left);
             let right_min = pop_minimum(&mut right);
-            
+
             distance += (left_min - right_min).abs();
         }
 
@@ -70,17 +74,26 @@ fn main() -> Result<()> {
     //endregion
 
     //region Part 2
-    // println!("\n=== Part 2 ===");
-    //
-    // fn part2<R: BufRead>(reader: R) -> Result<usize> {
-    //     Ok(0)
-    // }
-    //
-    // assert_eq!(0, part2(BufReader::new(TEST.as_bytes()))?);
-    //
-    // let input_file = BufReader::new(File::open(INPUT_FILE)?);
-    // let result = time_snippet!(part2(input_file)?);
-    // println!("Result = {}", result);
+    println!("\n=== Part 2 ===");
+
+    fn part2<R: BufRead>(reader: R) -> Result<usize> {
+        let (left, right) = read_challenge(reader);
+
+        let right_map = right.iter().counts();
+        let mut distance = 0;
+
+        for elem in left {
+            distance += (elem as usize) * right_map.get(&elem).unwrap_or(&0);
+        }
+
+        Ok(distance)
+    }
+
+    assert_eq!(31, part2(BufReader::new(TEST.as_bytes()))?);
+
+    let input_file = BufReader::new(File::open(INPUT_FILE)?);
+    let result = time_snippet!(part2(input_file)?);
+    println!("Result = {}", result);
     //endregion
 
     Ok(())