Advent of Code Day 1

I started playing around with Advent of Code1 this year.

For part 1, I used a spreadsheet to sum the numbers :P Here’s my solution for part 2:

found = False
u = set()
i = 0
while not found:
    for line in open("input1.txt"):
        i = i + int(line)
        if i in u:
            found = i
        print('.', end='', flush=True)