initial commit, includes days 1 and 2 solutions

src/day01.rs

@@ -0,0 +1,41 @@
+// ==== day 1
+
+use crate::utils;
+use anyhow::{anyhow, Result};
+
+fn day01_part1(data: &[i64]) -> Result<i64> {
+    for i in 0..data.len() - 2 {
+        for j in i + 1..data.len() - 1 {
+            if data[i] + data[j] == 2020 {
+                return Ok(data[i] * data[j]);
+            }
+        }
+    }
+    Err(anyhow!("no result found"))
+}
+
+fn day01_part2(data: &[i64]) -> Result<i64> {
+    for i in 0..data.len() - 3 {
+        for j in i + 1..data.len() - 2 {
+            for k in j + 1..data.len() - 1 {
+                if data[i] + data[j] + data[k] == 2020 {
+                    return Ok(data[i] * data[j] * data[k]);
+                }
+            }
+        }
+    }
+    Err(anyhow!("no result found"))
+}
+
+pub fn run() -> Result<(i64, i64)> {
+    let data = utils::read_i64s("data/input-01.txt")?;
+    let answers = utils::read_i64s("data/output-01.txt")?;
+
+    let p1 = day01_part1(&data)?;
+    assert_eq!(p1, answers[0]);
+
+    let p2 = day01_part2(&data)?;
+    assert_eq!(p2, answers[1]);
+
+    Ok((p1, p2))
+}