Completed day 1

day1/Cargo.lock

@@ -0,0 +1,14 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "anyhow"
+version = "1.0.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf8dcb5b4bbaa28653b647d8c77bd4ed40183b48882e130c1f1ffb73de069fd7"
+
+[[package]]
+name = "day1"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+]

day1/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "day1"
+version = "0.1.0"
+authors = ["Tyler Hallada <tyler@hallada.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = "1.0"

day1/input/input.txt

@@ -0,0 +1,200 @@
+1934
+1702
+1571
+1737
+1977
+1531
+1428
+1695
+1794
+1101
+13
+1164
+1235
+1289
+1736
+1814
+1363
+1147
+1111
+1431
+1765
+1515
+1184
+1036
+1803
+1791
+1638
+1809
+1283
+1980
+1854
+1878
+1574
+1352
+1151
+730
+1581
+1990
+1919
+2003
+1538
+1663
+1735
+1772
+1830
+1152
+1022
+1774
+1544
+1551
+1835
+1383
+1614
+1396
+1715
+1530
+295
+1208
+1978
+1104
+1691
+1176
+1183
+1909
+1192
+1535
+1924
+1268
+1969
+1954
+1760
+1077
+1734
+1371
+1676
+1933
+1400
+1928
+1982
+1541
+1106
+1248
+1346
+1782
+1142
+1849
+1798
+1362
+1379
+1886
+1265
+1226
+1751
+1575
+1027
+1710
+1601
+1205
+1922
+1452
+1206
+1263
+2000
+1957
+1951
+1834
+1533
+1149
+1245
+1564
+1182
+1237
+1013
+1254
+1895
+1504
+1480
+1556
+1821
+1589
+1864
+1573
+1698
+1927
+1434
+516
+1722
+1360
+1940
+1212
+1329
+1675
+1812
+1917
+1302
+1604
+1336
+1233
+1405
+1179
+1169
+1081
+1941
+1553
+1236
+1824
+1923
+1938
+1475
+1446
+1545
+1853
+1664
+317
+1489
+1884
+1743
+1621
+1128
+1474
+1505
+394
+1387
+1509
+1627
+1914
+1913
+1949
+1843
+1847
+1882
+1486
+1082
+1802
+1645
+1690
+1629
+1377
+2004
+1044
+1191
+1014
+1857
+1813
+1572
+1055
+1002
+1721
+1273
+1417
+1968
+1888
+1863
+1278
+1141
+1964
+1259
+1823
+1181
+1779

day1/input/test.txt

@@ -0,0 +1,6 @@
+1721
+979
+366
+299
+675
+1456

day1/src/main.rs

@@ -0,0 +1,67 @@
+use anyhow::{anyhow, Result};
+
+use std::fs::File;
+use std::io::prelude::*;
+use std::io::BufReader;
+
+const INPUT: &str = "input/input.txt";
+
+fn solve_part1(input_path: &str) -> Result<u32> {
+    let file = File::open(input_path)?;
+    let reader = BufReader::new(file);
+
+    let mut prev_lines = Vec::new();
+    for line in reader.lines() {
+        let number: u32 = line?.parse()?;
+        for prev_number in prev_lines.iter() {
+            if number + prev_number == 2020 {
+                return Ok(number * prev_number);
+            }
+        }
+        prev_lines.push(number);
+    }
+
+    Err(anyhow!("Found no pair of numbers that sums to 2020"))
+}
+
+fn solve_part2(input_path: &str) -> Result<u32> {
+    let file = File::open(input_path)?;
+    let reader = BufReader::new(file);
+
+    let mut prev_lines = Vec::new();
+    for line in reader.lines() {
+        let number: u32 = line?.parse()?;
+        for prev_number in prev_lines.iter() {
+            for third_number in prev_lines.iter() {
+                if number + prev_number + third_number == 2020 {
+                    return Ok(number * prev_number * third_number);
+                }
+            }
+        }
+        prev_lines.push(number);
+    }
+
+    Err(anyhow!("Found no three numbers that sum to 2020"))
+}
+
+fn main() {
+    println!("Part 1: {}", solve_part1(INPUT).unwrap());
+    println!("Part 2: {}", solve_part2(INPUT).unwrap());
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = "input/test.txt";
+
+    #[test]
+    fn solves_part1() {
+        assert_eq!(solve_part1(TEST_INPUT).unwrap(), 514579);
+    }
+
+    #[test]
+    fn solves_part2() {
+        assert_eq!(solve_part2(TEST_INPUT).unwrap(), 241861950);
+    }
+}