Day 1

Can we find pairs of numbers that add up to a total?

import pytest
import ipytest
ipytest.autoconfig()

import itertools

def find_pair(l, target):
    for (a,b) in itertools.combinations(l,2):
        if a+b == target:
            return (a,b)
    return (0,0)

Let's test some of that

assert (1,6) == find_pair([1,2,3,4,5,6], 7)
assert (1721,299) == find_pair([1721,979,366,299,675,1456], 2020)

Ok, so we can find pairs, let's find the pair from the actual input. This requires reading all the numbers from the data

data = [int(l) for l in open("day1.txt").readlines()]

find_pair(data, 2020)

(1073, 947)

Part 2

Great, so lets move onto day 2, now we need to find triples, rather than pairs. Should be easy, just change find_pair into find_triple and everything else is the same

def find_triple(l, target):
    for (a,b,c) in itertools.combinations(l,3):
        if a+b+c == target:
            return (a,b,c)
    return (0,0,0)

assert (1,2,6) ==  find_triple([1,2,3,4,5,6], 9)
assert (979, 366, 675) == find_triple([1721,979,366,299,675,1456], 2020)

Great, that works, so lets now run it against the real data

find_triple(data, 2020)

(911, 618, 491)