day 1, 2 stars

.gitignore

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+target

1/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "array-append"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "725731b5abb5b99ed3237a756dd6c6723911f973d998c0e756671f92df20bfec"
+
+[[package]]
+name = "day1"
+version = "0.1.0"
+dependencies = [
+ "array-append",
+]

1/Cargo.toml

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+[package]
+name = "day1"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+array-append = "0.1.0"

1/src/main.rs

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+use std::fs::File;
+use std::io::{self, BufRead, BufReader};
+
+const PATH: &str = "./input.txt";
+
+fn main() {
+    // 1. read file
+    // 2. loop line by line
+    // 3. count all values
+    // 4. if \n, check sum
+
+    let mut highest_sum: i32 = 0;
+    let mut new_sum: i32 = 0;
+
+    let mut highest_sums: Vec<i32> = Vec::new();
+
+    let lines = read_lines(PATH);
+    for result in lines {
+        let line = result.unwrap();
+
+        if line == "" {
+            highest_sum = check_highest_sum(&new_sum, &highest_sum);
+            new_sum = 0;
+        } else {
+            new_sum += line.parse::<i32>().unwrap();
+            check_3_highest(&new_sum, &mut highest_sums);
+        }
+    }
+
+    println!("1. RESULT: {}", highest_sum);
+    println!("2. RESULT {:?}", calc_final_result(highest_sums));
+}
+
+fn check_highest_sum(new_sum: &i32, highest_sum: &i32) -> i32 {
+    if *new_sum > *highest_sum {
+        *new_sum
+    } else {
+        *highest_sum
+    }
+}
+
+fn check_3_highest(new_sum: &i32, highest_sums: &mut Vec<i32>) {
+    if highest_sums.len() < 3 {
+        highest_sums.push(*new_sum);
+        return;
+    }
+
+    highest_sums.sort();
+    highest_sums.reverse();
+
+    println!(
+        "{} > {} = {}",
+        *new_sum,
+        *highest_sums.last().unwrap(),
+        *new_sum > highest_sums[0]
+    );
+
+    if *new_sum > *highest_sums.last().unwrap() {
+        highest_sums.pop();
+        highest_sums.push(*new_sum);
+    }
+    println!("{:?}", highest_sums);
+}
+
+fn calc_final_result(sum: Vec<i32>) -> i32 {
+    sum.iter().sum()
+}
+
+fn read_lines(filename: &str) -> io::Lines<BufReader<File>> {
+    let file = File::open(filename).unwrap();
+    return io::BufReader::new(file).lines();
+}