From fca5536f60962202c5917528ed0441afd3d87297 Mon Sep 17 00:00:00 2001
From: Karl Spickermann <karlhspickermann@gmail.de>
Date: Tue, 1 Dec 2020 17:08:12 +0100
Subject: [PATCH] Day1

---
 day1/day1.go       |  61 ++++++++++++++
 day1/day1Test.txt  |   6 ++
 day1/day1input.txt | 200 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 267 insertions(+)
 create mode 100644 day1/day1.go
 create mode 100644 day1/day1Test.txt
 create mode 100644 day1/day1input.txt

diff --git a/day1/day1.go b/day1/day1.go
new file mode 100644
index 0000000..e1244b2
--- /dev/null
+++ b/day1/day1.go
@@ -0,0 +1,61 @@
+package main
+
+import (
+	"AoC2020/helper"
+	"errors"
+	"fmt"
+	"os"
+	"sort"
+)
+
+func main() {
+	args := os.Args[1:]
+	input, err := helper.GetInput(args[0])
+	if err != nil {
+		fmt.Println(err)
+	}
+	fmt.Println(day1(input))
+	fmt.Println(day1_part2(input))
+
+}
+
+func day1(numbers []int) int {
+	goal := 2020
+	sort.Ints(numbers)
+	p1 := 0
+	p2 := len(numbers) - 1
+	for {
+		if numbers[p1]+numbers[p2] < goal {
+			p1++
+		}
+		if numbers[p1]+numbers[p2] > goal {
+			p2--
+		}
+		if numbers[p1]+numbers[p2] == goal {
+			return numbers[p1] * numbers[p2]
+		}
+	}
+}
+
+func day1_part2(numbers []int) (int, error) {
+	goal := 2020
+	sort.Ints(numbers)
+
+	for i, number := range numbers {
+		p1 := i + 1
+		p2 := len(numbers) - 1 - i
+
+		for p1 < p2 {
+			if numbers[p1]+numbers[p2]+number < goal {
+				p1++
+			}
+			if numbers[p1]+numbers[p2]+number > goal {
+				p2--
+			}
+			if numbers[p1]+numbers[p2]+number == goal {
+				return numbers[p1] * numbers[p2] * number, nil
+			}
+		}
+	}
+	return 0, errors.New("No Triplet Found")
+}
diff --git a/day1/day1Test.txt b/day1/day1Test.txt
new file mode 100644
index 0000000..0bb977d
--- /dev/null
+++ b/day1/day1Test.txt
@@ -0,0 +1,6 @@
+1721
+979
+366
+299
+675
+1456
\ No newline at end of file
diff --git a/day1/day1input.txt b/day1/day1input.txt
new file mode 100644
index 0000000..c13d4c4
--- /dev/null
+++ b/day1/day1input.txt
@@ -0,0 +1,200 @@
+1728
+1621
+1856
+1683
+1940
+1097
+1711
+1906
+2008
+1608
+2003
+1990
+1864
+1035
+1981
+1978
+1955
+1907
+1198
+1087
+1835
+1961
+1941
+1903
+1675
+417
+1842
+1802
+1639
+1601
+1546
+1909
+1061
+1031
+1996
+1717
+1972
+1900
+1443
+1873
+1851
+2010
+1650
+1975
+1002
+1142
+1747
+1640
+1924
+1824
+1539
+1937
+1715
+1871
+1867
+1428
+1861
+1914
+1986
+1976
+1111
+1858
+1869
+1899
+1171
+1041
+1662
+1222
+1709
+1889
+1950
+1960
+1989
+1737
+1600
+1444
+1725
+1710
+1653
+1745
+1922
+1945
+1189
+1917
+1891
+1718
+1997
+1631
+1053
+1750
+1634
+1822
+1706
+1160
+1619
+1665
+1687
+1648
+1818
+1655
+1736
+1881
+489
+1598
+1923
+1962
+1918
+1689
+1616
+1825
+1723
+1767
+591
+1734
+1949
+1645
+1344
+1959
+1758
+1068
+1843
+1826
+1849
+2005
+1777
+144
+2009
+1982
+1911
+1288
+1595
+1094
+2000
+1713
+1973
+1971
+1916
+1666
+1105
+1806
+1868
+1944
+1654
+1809
+1726
+1672
+1060
+1065
+1521
+1921
+1966
+1113
+1149
+1607
+1980
+1023
+1855
+1948
+1638
+1930
+1866
+1954
+1697
+1884
+1832
+2004
+914
+1845
+1043
+1854
+1223
+1913
+1984
+1910
+1793
+1878
+1248
+617
+1927
+1527
+1819
+1350
+1807
+1722
+1016
+1700
+111
+1629
+1932
+1644
+1454
+1987
+1925
+1953
+1743
+1180
+1782
+1523
+1245
+1620