2025/day-06: Solve part 2

2025/rust/day-06/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day-06"
+version = "0.1.0"

2025/rust/day-06/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day-06"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

2025/rust/day-06/src/main.rs

@@ -0,0 +1,127 @@
+use std::{fmt::Debug, fs, str::FromStr};
+
+#[derive(PartialEq, Debug)]
+enum Operation {
+    Add,
+    Multiply,
+}
+
+impl FromStr for Operation {
+    type Err = ();
+
+    fn from_str(input: &str) -> Result<Operation, Self::Err> {
+        match input {
+            "+" => Ok(Operation::Add),
+            "*" => Ok(Operation::Multiply),
+            _ => Err(()),
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Problem {
+    numbers: Vec<u64>,
+    operation: Operation,
+}
+
+impl Problem {
+    fn solve(&self) -> u64 {
+        match self.operation {
+            Operation::Add => self.numbers.iter().sum(),
+            Operation::Multiply => self.numbers.iter().product(),
+        }
+    }
+}
+
+fn main() {
+    let content = &mut fs::read_to_string("../../inputs/06.txt").unwrap();
+
+    println!("Grand total 1: {}", grand_total(&parse_input_v1(content)));
+    println!("Grand total 2: {}", grand_total(&parse_input_v2(content)));
+}
+
+fn parse_input_v1(contents: &str) -> Vec<Problem> {
+    let grid: Vec<Vec<&str>> = contents
+        .trim()
+        .lines()
+        .map(|line| line.split_whitespace().collect())
+        .collect();
+
+    let operations_row = grid.last().unwrap();
+    let num_cols = grid[0].len();
+
+    (0..num_cols)
+        .map(|col_index| {
+            let operation = Operation::from_str(operations_row[col_index]).unwrap();
+
+            let numbers = grid[..grid.len() - 1]
+                .iter()
+                .map(|row| row[col_index].parse().unwrap())
+                .collect();
+
+            Problem { numbers, operation }
+        })
+        .collect()
+}
+
+fn parse_input_v2(contents: &str) -> Vec<Problem> {
+    let grid: Vec<Vec<u8>> = contents
+        .trim_end_matches('\n')
+        .lines()
+        .map(|line| line.as_bytes().to_vec())
+        .collect();
+
+    let operations_row = grid.last().unwrap();
+
+    let mut problems = Vec::new();
+
+    let mut numbers = Vec::new();
+    let mut operation = Operation::Add;
+
+    for col in 0..grid[0].len() {
+        if let Ok(op) = Operation::from_str(&(operations_row[col] as char).to_string()) {
+            operation = op;
+        }
+
+        let column: String = (0..grid.len() - 1)
+            .map(|row| grid[row][col] as char)
+            .filter(|c| !c.is_whitespace())
+            .collect();
+
+        if column.is_empty() {
+            problems.push(Problem { numbers, operation });
+            numbers = Vec::new();
+            operation = Operation::Add;
+        } else {
+            numbers.push(column.parse().unwrap());
+        }
+    }
+    problems.push(Problem { numbers, operation });
+
+    problems
+}
+
+fn grand_total(problems: &[Problem]) -> u64 {
+    problems.iter().map(Problem::solve).sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = "123 328  51 64 
+ 45 64  387 23 
+  6 98  215 314
+*   +   *   +  
+";
+
+    #[test]
+    fn test_part1() {
+        assert_eq!(grand_total(&parse_input_v1(TEST_INPUT)), 4277556);
+    }
+
+    #[test]
+    fn test_part2() {
+        assert_eq!(grand_total(&parse_input_v2(TEST_INPUT)), 3263827);
+    }
+}

flake.lock

@@ -3,10 +3,10 @@
     "inputs": {
       "flake": false,
       "locked": {
-        "lastModified": 1764926544,
+        "lastModified": 1765025072,
-        "narHash": "sha256-xIkgV9KrBel6Qwy673iMmmggFGZ9Zz93Hd/lGhRyHRM=",
+        "narHash": "sha256-mTX6WtSh/OWj4nAsDdr8fkAOPZgANHQc/DURFczQBC4=",
         "ref": "refs/heads/main",
-        "rev": "27de1eaccb499f25dca8f3505b4c4f42a8e35514",
+        "rev": "b425d990c6bf65f69566c0167e1ff8049c87bc2a",
         "shallow": true,
         "type": "git",
         "url": "ssh://git@github.com/SebastianStork/advent-of-code-inputs.git"