2020 Day 01

2020/01/README.md

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+# 2020 Day 1: Report Repair 
+Copyright (c) Eric Wastl
+#### [Direct Link](https://adventofcode.com/2020/day/1)
+
+## Part 1
+
+Before you leave, the Elves in accounting just need you to fix your **expense report** (your puzzle input); apparently, something isn't quite adding up.
+
+Specifically, they need you to **find the two entries that sum to `2020`** and then multiply those two numbers together.
+
+For example, suppose your expense report contained the following:
+
+```
+1721
+979
+366
+299
+675
+1456
+```
+
+In this list, the two entries that sum to `2020` are `1721` and `299`. Multiplying them together produces `1721 * 299 = 514579`, so the correct answer is **`514579`**.
+
+Of course, your expense report is much larger. **Find the two entries that sum to `2020`; what do you get if you multiply them together?**
+
+## Part 2
+
+The Elves in accounting are thankful for your help; one of them even offers you a starfish coin they had left over from a past vacation. They offer you a second one if you can find **three** numbers in your expense report that meet the same criteria.
+
+Using the above example again, the three entries that sum to `2020` are `979`, `366`, and `675`. Multiplying them together produces the answer, **`241861950`**.
+
+In your expense report, **what is the product of the three entries that sum to `2020`**?

2020/01/code.py

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+""" https://adventofcode.com/2020/day/1 """
+
+def readFile() -> list:
+    with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
+        return [int(line[:-1]) for line in f.readlines()]
+
+def part1(vals: list) -> int:
+    for val in vals:
+        if (2020 - val) in vals:
+            return (2020 - val) * val
+
+def part2(vals: list) -> int:
+    for i in range(len(vals)):
+        for j in range(i, len(vals)):
+            if (2020 - vals[i] - vals[j]) in vals:
+                return vals[i] * vals[j] *  (2020 - vals[i] - vals[j])
+
+
+def test():
+    test_input = [1721, 979, 366, 299, 675, 1456]
+    assert part1(test_input) == 514579
+    assert part2(test_input) == 241861950
+
+if __name__ == "__main__":
+    test()
+    vals = readFile()
+    print(f"Part 1: {part1(vals)}")
+    print(f"Part 2: {part2(vals)}")

2020/01/input.txt

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+1650
+1174
+1156
+1874
+1958
+1918
+1980
+1588
+1863
+1656
+1843
+1738
+2001
+1883
+1941
+1602
+1881
+1927
+1284
+1474
+1942
+1992
+1925
+1990
+1831
+1907
+1914
+1815
+1921
+1589
+1224
+1148
+1223
+935
+1726
+1828
+1838
+1611
+1960
+1668
+1744
+1566
+1902
+1203
+1975
+1225
+2000
+1678
+1950
+572
+1812
+1568
+1484
+1767
+1509
+1658
+1127
+1870
+1098
+1294
+1310
+1483
+1865
+1967
+1856
+1963
+1929
+1119
+132
+1969
+1094
+1523
+1701
+1896
+1631
+1956
+1910
+1672
+1232
+1285
+1761
+1649
+1931
+1959
+1191
+1846
+1908
+1976
+1500
+1940
+1924
+1521
+1989
+1635
+1102
+1114
+1948
+2007
+1964
+1926
+1590
+1900
+1690
+1880
+1596
+1395
+1373
+1937
+1833
+1845
+1949
+1128
+1218
+1928
+1912
+1893
+1869
+960
+1813
+1645
+1490
+1318
+1934
+1259
+2005
+1522
+1270
+1089
+1674
+1997
+1112
+1954
+1769
+1829
+1814
+1922
+1904
+1894
+1595
+1103
+237
+1943
+1364
+1906
+1971
+1998
+1461
+1606
+1911
+1545
+1952
+1917
+1582
+1994
+1946
+1935
+1844
+1938
+1633
+2004
+1132
+1530
+1915
+1982
+1871
+1852
+1613
+1476
+1216
+1834
+1939
+409
+1895
+1120
+1194
+1135
+1899
+1901
+1439
+485
+1855
+1136
+200
+1887
+250
+1930
+1506
+1945
+1988
+1170
+1575
+1872
+1261
+1137
+1978
+1537
+1897
+1837
+1753
+1913

2020/01/solution.txt

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+Part 1: 658899
+Part 2: 155806250