2024 - Day 1 part 2 - rust

2024/rust1_2/.gitignore

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+target
+Cargo.lock

2024/rust1_2/Cargo.toml

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+[package]
+name = "rust1_2"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

2024/rust1_2/src/main.rs

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+use std::io::{BufRead, BufReader};
+use std::fs::File;
+use std::collections::HashMap;
+
+fn main (){
+    // let filename = "../1/input_example.txt";
+    let filename = "../1/input.txt";
+    let file = BufReader::new(File::open(filename).expect("Unable to open file"));
+    let mut accum: u32 = 0;
+
+    let mut list1: Vec<u32> = vec![];
+    let mut counters: HashMap<u32, u32> = HashMap::new();
+
+    for line in file.lines() { 
+        let wline = line.unwrap();
+        let nums: Vec<&str> = wline.split(' ')
+            .filter(|&x| !x.is_empty())
+            .collect();
+
+        list1.push(nums[0].parse().unwrap());
+
+        counters.entry(nums[1].parse().unwrap())
+            .and_modify(|e| {*e += 1})
+            .or_insert(1);
+    }
+
+    for n in list1 {
+        if counters.contains_key(&n){
+            accum += n * counters[&n];
+        }
+    }
+
+    println!("{}", accum);
+}