Day 1 Part 1

day1/README

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+Day 1 Notes
+
+Part1:
+
+$ elixir day1part1.exs
+618 x 1402 = 866436

day1/day1part1.exs

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+defmodule Day1Part1 do
+  def run do
+    {a, b} =
+      File.read!("input")
+      |> String.trim()
+      |> String.split("\n")
+      |> Enum.map(&String.to_integer/1)
+      |> find_2020()
+
+    IO.puts("#{a} x #{b} = #{a * b}")
+  end
+
+  def find_2020([current | rest]) do
+    target = 2020 - current
+
+    if Enum.member?(rest, target) do
+      {current, target}
+    else
+      find_2020(rest)
+    end
+  end
+end
+
+Day1Part1.run()

day1/input

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+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