JSFiddle - React, Tailwind, and code Playground

by kapantzak

JavaScript

const input = `1981
1415
1767
1725
1656
1860
1272
1582
1668
1202
1360
1399
1517
1063
1773
1194
1104
1652
1316
1883
1117
522
1212
1081
1579
1571
1393
243
1334
1934
1912
1784
1648
1881
1362
1974
1592
1639
1578
1650
1771
1384
1374
1569
1785
1964
1910
1787
1865
1373
1678
1708
1147
1426
1323
855
1257
1497
1326
1764
1793
1993
1926
1387
1441
1332
1018
1949
1807
1431
1933
2009
1840
1628
475
1601
1903
1294
1942
1080
1817
1848
1097
1600
1833
1665
1919
1408
1963
1140
1558
1847
1491
1367
1826
1454
1714
2003
1378
1301
1520
1269
1820
1252
1760
1135
1893
1904
1956
1344
1743
1358
1489
1174
1675
1765
1093
1543
1940
1634
1778
1732
1423
1308
1855
962
1873
1692
1485
1766
1287
1388
1671
1002
1524
1891
1627
1155
1185
1122
1603
1989
1343
1745
1868
1166
1253
1136
1803
1733
1310
1762
1319
1930
1637
1726
1446
266
1121
1851
1819
1284
1959
1449
1965
1687
1079
1808
1839
1626
1359
1935
1247
1932
1951
1318
1597
1268
643
1938
1741
1721
1640
1238
1976
1237
1960
1805
1757
1990
1276
1157
1469
1794
1914
1982
1115
1907
1846
1674`;

const numbers = input.split('\n').map(x => Number(x)).sort((a,b) => a-b);
//console.log(arr);
function getProductOfSums(arr, sum) {
	for (let i = 0; i < arr.length; i++) {
    for (let n = arr.length - 1; n >= i; n--) {
      if (arr[i] + arr[n] === sum) {
        return arr[i] * arr[n];
      }
    }
  }
  return null;
}
//console.log(getProductOfSums(numbers, 2020));
for (let i = 0; i < arr.length; i++) {
	const n = arr[i];
  const nums = arr.slice(i+1);
  const product = getProductOfSums(nums, 2020 - n);
  if (product) {
  	return product * n;
  }
}