Day 7

src/bin/day7.rs

@@ -0,0 +1,116 @@
+use std::time::Instant;
+
+use aoc_2024::{load, print_res};
+use bstr::BString;
+use color_eyre::eyre::Context;
+
+type Parsed = Vec<(u64, Vec<u64>)>;
+
+#[inline(never)]
+pub fn parsing(input: &BString) -> color_eyre::Result<Parsed> {
+    core::str::from_utf8(input)?
+        .lines()
+        .map(|line| {
+            let Some((result, values)) = line.split_once(':') else {
+                color_eyre::eyre::bail!("Missing `:` in '{line}'");
+            };
+
+            Ok((
+                result.parse().with_context(|| "could not parse result")?,
+                values
+                    .split_whitespace()
+                    .map(|n| n.parse().with_context(|| "could not parse value `{n}`"))
+                    .collect::<Result<_, _>>()
+                    .with_context(|| "could not parse values")?,
+            ))
+        })
+        .collect()
+}
+
+#[inline(never)]
+pub fn part1(input: Parsed) {
+    let mut total_calibration_result = 0;
+
+    for (result, values) in input {
+        let mut totals = vec![values[0]];
+
+        for v in &values[1..] {
+            let mut new = Vec::with_capacity(totals.len() * 2);
+            for total in totals {
+                let p = total + v;
+                if p <= result {
+                    new.push(p);
+                }
+
+                let m = total * v;
+                if m <= result {
+                    new.push(m);
+                }
+            }
+            totals = new;
+        }
+
+        if totals.contains(&result) {
+            total_calibration_result += result;
+        }
+    }
+
+    print_res!("Total calibration result: {total_calibration_result}")
+}
+
+#[inline(never)]
+pub fn part2(input: Parsed) {
+    let mut total_calibration_result = 0;
+
+    for (result, values) in input {
+        let mut totals = vec![values[0]];
+
+        for v in &values[1..] {
+            let mut new = Vec::with_capacity(totals.len() * 3);
+            for total in totals {
+                let p = total + v;
+                if p <= result {
+                    new.push(p);
+                }
+
+                let m = total * v;
+                if m <= result {
+                    new.push(m);
+                }
+
+                let c = total * 10u64.pow(v.ilog10() + 1) + v;
+                if c <= result {
+                    new.push(c);
+                }
+            }
+            totals = new;
+        }
+
+        if totals.contains(&result) {
+            total_calibration_result += result;
+        }
+    }
+
+    print_res!("Total calibration result: {total_calibration_result}")
+}
+
+pub fn main() -> color_eyre::Result<()> {
+    let context = load()?;
+
+    let start = Instant::now();
+    let parsed = parsing(&context.input)?;
+    let elapsed = humantime::format_duration(start.elapsed());
+
+    let start = Instant::now();
+    if context.part == 1 {
+        part1(parsed);
+    } else {
+        part2(parsed);
+    }
+    let elapsed_part = humantime::format_duration(start.elapsed());
+
+    println!("  Parsing: {elapsed}");
+    println!("  Solving: {elapsed_part}");
+
+    Ok(())
+}