Advent of Code 2020 Day 1

— Day 1: Report Repair —

The elves give you an expense report and need you to fix things up.

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?

import itertools

with open('data-2020-01.txt', 'r') as f:
    inp = f.read().splitlines()

Loop through

# want integer not strings
my_input = [int(i) for i in inp]

# probably a good idea
my_input.sort()

# for loops
for x in my_input:
  for y in my_input:
    if x + y == 2020:
      print(x * y)

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— Part Two —

Actually, find three numbers that sum to 2020.

In your expense report, what is the product of the three entries that sum to 2020?

# itertools
for x, y in itertools.product(my_input, my_input):
  if x + y == 2020:
    print(x * y)
    break

# generator
for x, y in ((xx, yy) for xx in my_input for yy in my_input):
  if x + y == 2020:
    print(x * y)
    break

# triple itertools
for x, y, z in itertools.product(my_input, my_input, my_input):
  if x + y + z == 2020:
    print(x * y * z)
    break

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Code stolen from Python from R slack, courtesy of Zach Ingbretsen

def find_sum_combs(inputs, total=2020, n=2):
    for comb in itertools.combinations(inputs, n):
        if sum(comb) == total:
            return comb
            

x, y = find_sum_combs(my_input)
print(x*y)

x, y, z = find_sum_combs(my_input, n=3)
print(x*y*z)

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