Add solution for 2020 day 01

2020/README.md

@@ -1,28 +1,29 @@
 # [Advent of Code 2020](https://adventofcode.com/2020)
 
-## Progress
-- [ ] Day 01
-- [ ] Day 02
-- [ ] Day 03
-- [ ] Day 04
-- [ ] Day 05
-- [ ] Day 06
-- [ ] Day 07
-- [ ] Day 08
-- [ ] Day 09
-- [ ] Day 10
-- [ ] Day 11
-- [ ] Day 12
-- [ ] Day 13
-- [ ] Day 14
-- [ ] Day 15
-- [ ] Day 16
-- [ ] Day 17
-- [ ] Day 18
-- [ ] Day 19
-- [ ] Day 20
-- [ ] Day 21
-- [ ] Day 22
-- [ ] Day 23
-- [ ] Day 24
-- [ ] Day 25
+| Solved | Day | Language |
+| :----: | :-: | :------- |
+|   ✓    | 01  | Rust     |
+|        | 02  |          |
+|        | 03  |          |
+|        | 04  |          |
+|        | 05  |          |
+|        | 06  |          |
+|        | 07  |          |
+|        | 08  |          |
+|        | 09  |          |
+|        | 10  |          |
+|        | 11  |          |
+|        | 12  |          |
+|        | 13  |          |
+|        | 14  |          |
+|        | 15  |          |
+|        | 16  |          |
+|        | 17  |          |
+|        | 18  |          |
+|        | 19  |          |
+|        | 20  |          |
+|        | 21  |          |
+|        | 22  |          |
+|        | 23  |          |
+|        | 24  |          |
+|        | 25  |          |

2020/day-01/.gitignore

@@ -0,0 +1,2 @@
+part_one
+part_two

2020/day-01/common.rs

@@ -0,0 +1,15 @@
+use std::env;
+use std::fs::File;
+use std::io::Read;
+
+pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+pub fn read_file() -> Result<Vec<u32>> {
+    let path = env::args().skip(1).next().unwrap();
+
+    let mut file = File::open(path)?;
+    let mut content = String::new();
+    file.read_to_string(&mut content)?;
+
+    Ok(content.lines().map(|l| l.parse().unwrap()).collect())
+}

2020/day-01/inputs/puzzle.txt

@@ -0,0 +1,200 @@
+1028
+1987
+1938
+1136
+1503
+1456
+1107
+1535
+1946
+1986
+855
+1587
+1632
+1548
+1384
+1894
+1092
+1876
+1914
+1974
+1662
+1608
+2004
+1464
+1557
+1485
+1267
+1582
+1307
+1903
+1102
+1578
+1421
+1184
+1290
+1786
+1295
+1930
+1131
+1802
+1685
+1735
+1498
+1052
+1688
+990
+1805
+1768
+1922
+1781
+1897
+1545
+1591
+1393
+1186
+149
+1619
+1813
+1708
+1119
+1214
+1705
+1942
+1684
+1460
+1123
+1439
+1672
+1980
+1337
+1731
+1203
+1481
+2009
+1110
+1116
+1443
+1957
+1891
+1595
+1951
+1883
+1733
+1697
+1321
+1689
+1103
+1300
+1262
+1190
+1667
+1843
+1544
+1877
+1718
+1866
+1929
+1169
+1693
+1518
+1375
+1477
+1222
+1791
+1612
+1373
+1253
+1087
+1959
+1970
+1112
+1778
+1412
+1127
+1767
+1091
+1653
+1609
+1810
+1912
+1917
+935
+1499
+1878
+1452
+1935
+1937
+968
+1905
+1077
+1701
+1789
+1506
+1451
+1125
+1686
+1117
+1991
+1215
+1776
+1976
+846
+1923
+1945
+1888
+1193
+1146
+1583
+1315
+1372
+1963
+1491
+1777
+1799
+1363
+1579
+1367
+1863
+1983
+1679
+1944
+1654
+1953
+1297
+530
+1502
+1738
+1934
+1185
+1998
+1764
+1856
+1207
+1181
+1494
+1676
+1900
+1057
+339
+1994
+2006
+1536
+2007
+644
+1173
+1692
+1493
+1756
+1916
+1890
+1908
+1887
+1241
+1447
+1997
+1967
+1098
+1287
+1392
+1932

2020/day-01/inputs/sample.txt

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

2020/day-01/part_one.rs

@@ -0,0 +1,21 @@
+mod common;
+
+use common::{read_file, Result};
+
+fn main() -> Result<()> {
+    let entries = read_file()?;
+
+    let mut skip_inner = 0;
+
+    for outer in &entries {
+        for inner in entries.iter().skip(skip_inner) {
+            if outer + inner == 2020 {
+                println!("{}", outer * inner);
+                return Ok(());
+            }
+        }
+        skip_inner += 1;
+    }
+
+    Ok(())
+}

2020/day-01/part_two.rs

@@ -0,0 +1,26 @@
+mod common;
+
+use common::{read_file, Result};
+
+fn main() -> Result<()> {
+    let entries = read_file()?;
+
+    let mut skip_inner = 0;
+
+    for outer in &entries {
+        let mut skip_innermost = 0;
+
+        for inner in entries.iter().skip(skip_inner) {
+            for innermost in entries.iter().skip(skip_innermost) {
+                if outer + inner + innermost == 2020 {
+                    println!("{}", outer * inner * innermost);
+                    return Ok(());
+                }
+            }
+            skip_innermost += 1;
+        }
+        skip_inner += 1;
+    }
+
+    Ok(())
+}