day 1

README.txt

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+Advent of Code
+
+https://adventofcode.com/2020

day-1/numbers.txt

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+1735
+1700
+1358
+1908
+1634
+2006
+762
+1492
+1917
+1591
+1571
+1283
+1744
+1815
+1383
+1787
+1832
+1032
+1845
+1406
+1978
+1263
+1450
+1364
+1594
+1877
+1346
+1695
+1501
+1266
+1729
+1476
+1558
+1684
+1295
+1267
+1341
+1415
+1491
+1640
+1756
+1330
+1987
+1969
+1844
+1706
+1654
+1580
+1405
+1419
+1367
+1277
+1992
+1953
+1499
+1470
+2000
+1739
+1889
+1670
+1776
+1798
+1308
+1890
+1626
+1284
+1315
+1869
+1514
+1214
+1648
+1418
+1329
+1795
+1385
+1477
+1984
+1796
+1515
+2001
+1155
+1800
+1965
+1971
+1100
+1650
+1686
+1911
+1560
+1912
+1721
+1658
+1738
+1885
+1028
+266
+1989
+1704
+1388
+1498
+1769
+1453
+925
+1588
+1828
+1024
+1671
+1998
+1942
+1636
+1382
+993
+1703
+1475
+1391
+1970
+1841
+1952
+1446
+1347
+1395
+1440
+1980
+1386
+1922
+1857
+1291
+1808
+1335
+1876
+1576
+1436
+634
+1557
+1782
+1881
+1955
+1765
+1736
+1585
+1858
+1862
+989
+1661
+1757
+1775
+1693
+1842
+1660
+1647
+870
+1928
+1597
+1420
+1646
+1821
+2009
+1866
+1947
+1593
+1788
+1369
+1525
+1256
+1846
+1445
+1907
+1750
+1906
+1849
+765
+1342
+1811
+1260
+1466
+1424
+1823
+1767
+1290
+1840
+1825
+1287
+1384
+1996
+1627
+1983
+1328
+1674
+1676
+1727
+1810
+1394
+799
+1723
+1293
+1273
+1317
+1749
+1552
+1645

day-1/package.json

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+{
+  "name": "day-1",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "part_one": "node part_one.js",
+    "part_two": "node part_two.js"
+  },
+  "author": "",
+  "license": "ISC"
+}

day-1/part_one.js

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+const fs = require('fs')
+const { exit } = require('process')
+const readline = require('readline')
+
+let numbers = new Set()
+fs.readFile('numbers.txt', 'utf-8', (err, data) => {
+    data.split('\n').forEach(numberString => {
+        const number = parseInt(numberString)
+        if (numbers.has(2020 - number)) {
+            console.log("Part 1:")
+            console.log(`The numbers are ${number} and ${2020 - number}`)
+            console.log(`The answer is ${number * (2020 - number)}`)
+            exit(0)
+        }
+        numbers.add(number)
+    })
+})

day-1/part_two.js

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+const fs = require('fs')
+const { exit } = require('process')
+const readline = require('readline')
+
+let baseNumbers = new Set()
+let sumNumbers = new Set()
+let sumNumberLookup = new Map()
+
+fs.readFile('numbers.txt', 'utf-8', (err, data) => {
+    data.split('\n').forEach(numberString => {
+        const number = parseInt(numberString)
+        if (sumNumbers.has(2020 - number)) {
+            let otherNumbers = sumNumberLookup[2020 - number]
+
+            console.log("Part 2:")
+            console.log(`The numbers are ${number}, ${otherNumbers[0]} and ${otherNumbers[1]}`)
+            console.log(`The answer is ${number * otherNumbers[0] * otherNumbers[1]}`)
+            exit(0)
+        }
+
+        baseNumbers.forEach(baseNumber => {
+            const sum = baseNumber + number
+            sumNumbers.add(sum)
+            sumNumberLookup[sum] = [baseNumber, number]
+        })
+        baseNumbers.add(number)
+    })
+})