puzzle 1-2

2 files changed, 32 insertions, 12 deletions

diff --git a/data/1-1.txt b/data/1.txt
index 15a9273..15a9273 100644
--- a/data/1-1.txt
+++ b/data/1.txt
diff --git a/src/2020/mod.rs b/src/2020/mod.rs
index 87c213b..27e56fc 100644
--- a/src/2020/mod.rs
+++ b/src/2020/mod.rs
@@ -4,13 +4,42 @@ use std::io::BufRead as _;
 pub fn run(day: u8, puzzle: u8) -> anyhow::Result<()> {
     match (day, puzzle) {
         (1, 1) => report_repair(),
+        (1, 2) => report_repair_2(),
         _ => Err(anyhow::anyhow!("unknown puzzle {}-{}", day, puzzle)),
     }
 }
 
 fn report_repair() -> anyhow::Result<()> {
-    let f = std::fs::File::open("data/1-1.txt")
-        .context("couldn't find data file")?;
+    let ints = read_ints("data/1.txt")?;
+    for i in &ints {
+        for j in &ints {
+            if i + j == 2020 {
+                println!("{} * {} = {}", i, j, i * j);
+                return Ok(());
+            }
+        }
+    }
+    Err(anyhow::anyhow!("no numbers summing to 2020 found"))
+}
+
+fn report_repair_2() -> anyhow::Result<()> {
+    let ints = read_ints("data/1.txt")?;
+    for i in &ints {
+        for j in &ints {
+            for k in &ints {
+                if i + j + k == 2020 {
+                    println!("{} * {} * {} = {}", i, j, k, i * j * k);
+                    return Ok(());
+                }
+            }
+        }
+    }
+    Err(anyhow::anyhow!("no numbers summing to 2020 found"))
+}
+
+fn read_ints(filename: &str) -> anyhow::Result<Vec<i32>> {
+    let f = std::fs::File::open(filename)
+        .with_context(|| format!("couldn't find data file {}", filename))?;
     let f = std::io::BufReader::new(f);
     let ints: anyhow::Result<Vec<i32>> = f
         .lines()
@@ -20,14 +49,5 @@ fn report_repair() -> anyhow::Result<()> {
                 .context("failed to parse line into an integer")
         })
         .collect();
-    let ints = ints?;
-    for i in &ints {
-        for j in &ints {
-            if i + j == 2020 {
-                println!("{} + {} = {}", i, j, i * j);
-                return Ok(());
-            }
-        }
-    }
-    Err(anyhow::anyhow!("no numbers summing to 2020 found"))
+    ints
 }