[2020-12-01] Add solutions for day01

Makefile

@@ -3,6 +3,8 @@
 all: day01 day02 day03 day04 day05 day06 day07 day08 day09 day10 day11 day12 day13 day14 day15 day16 day17 day18 day19 day20 day21 day22 day23 day24 day25
 
 day01:
+	go run main.go day01 input
+
 day02:
 day03:
 day04:

day01/example.txt

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

day01/input.txt

@@ -0,0 +1,200 @@
+1567
+1223
+1758
+1842
+1933
+1898
+1409
+1058
+1533
+1417
+1032
+1634
+1477
+1394
+1888
+1972
+1237
+1390
+1677
+1546
+1302
+1070
+1369
+1455
+1065
+1924
+1593
+1131
+1064
+1346
+1914
+1129
+1830
+1450
+1278
+1740
+1809
+1176
+1734
+1102
+1807
+1982
+1603
+1736
+2008
+1980
+1905
+1633
+1732
+1350
+1865
+1988
+1805
+1998
+1152
+1046
+1870
+1557
+1789
+1766
+1945
+1359
+1002
+1126
+1719
+1497
+1296
+1560
+1936
+1929
+1464
+2005
+1281
+618
+1257
+1107
+1632
+1688
+1964
+1803
+1360
+1384
+1889
+1411
+1328
+1452
+1868
+1515
+1586
+1631
+1618
+1087
+1710
+1094
+1774
+1295
+1700
+1636
+1230
+1421
+1910
+1522
+1366
+1144
+1757
+1493
+1316
+1103
+687
+1371
+1720
+1155
+1559
+1900
+989
+1367
+1999
+1066
+1773
+1787
+1402
+1047
+1806
+1956
+1219
+1555
+1307
+1419
+1706
+1884
+1109
+1181
+2010
+1298
+1730
+1078
+1848
+1398
+1687
+2007
+1550
+1664
+1225
+1079
+1698
+350
+1222
+1377
+1977
+1510
+1571
+1630
+1029
+1379
+1942
+1949
+1249
+1829
+1297
+1530
+1607
+1324
+1069
+1476
+928
+1039
+1855
+1644
+1454
+1310
+1172
+547
+1034
+1878
+1479
+1457
+1319
+1810
+1759
+1439
+1851
+545
+1470
+2003
+1908
+1564
+1491
+1174
+1301
+1689
+1276
+1781
+1392
+1499
+1962
+1653
+1823
+1381
+1827
+1974

day01/parse.go

@@ -0,0 +1,28 @@
+package day01
+
+import (
+	"log"
+	"sort"
+	"strconv"
+
+	"git.elis.nu/etu/aoc2020/utils"
+)
+
+var rows []int
+
+func ParseFile(input string) {
+	// Parse file
+	for _, line := range utils.GetLinesFromFile("day01/" + input + ".txt") {
+		row, err := strconv.Atoi(line)
+
+		if err != nil {
+			log.Println("Failed to parse int, skipping:", err)
+			continue
+		}
+
+		rows = append(rows, row)
+	}
+
+	// To reach the end state in a more consistent manner, sort the input
+	sort.Ints(rows)
+}

day01/solve1.go

@@ -0,0 +1,18 @@
+package day01
+
+import "log"
+
+func Solve1() {
+	for _, row1 := range rows {
+		for _, row2 := range rows {
+			if row1+row2 == 2020 {
+				log.Printf(
+					"2020-12-01.01: Answer: %d\n",
+					row1*row2,
+				)
+
+				return
+			}
+		}
+	}
+}

day01/solve2.go

@@ -0,0 +1,20 @@
+package day01
+
+import "log"
+
+func Solve2() {
+	for _, row1 := range rows {
+		for _, row2 := range rows {
+			for _, row3 := range rows {
+				if row1+row2+row3 == 2020 {
+					log.Printf(
+						"2020-12-01.02: Answer: %d\n",
+						row1*row2*row3,
+					)
+
+					return
+				}
+			}
+		}
+	}
+}

main.go

@@ -3,6 +3,9 @@ package main // import "git.elis.nu/etu/aoc2020"
 import (
 	"log"
 	"os"
+
+	"git.elis.nu/etu/aoc2020/day01"
+	"git.elis.nu/etu/aoc2020/utils"
 )
 
 func main() {
@@ -11,5 +14,7 @@ func main() {
 	}
 
 	switch os.Args[1] {
+	case "day01":
+		utils.Perf("2020-12-01", day01.ParseFile, day01.Solve1, day01.Solve2)
 	}
 }