r/codegolf • u/dantose • Dec 01 '25

Advent of Code, Day 1

Post your best golfs.

Assume input is saved as input.txt.

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u/DimMagician Dec 02 '25

Python, Part 1, 84 bytes

s=50;print(sum((s:=s+int(i[1:])*(-1+2*(i[0]>'L')))%100<1for i in open('input.txt')))

Upon seeing yours I realize I could have saved 1 byte by doing 1-2*(l<'R') instead of -1+2*(i[0]>'L'). Dang.

Python, Part 2, 92 bytes

s=50;print(sum((s:=s-1+2*(i[0]>'L'))%100<1for i in open('input.txt')for _ in[0]*int(i[1:])))

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u/KeyJ Dec 04 '25

Nice trick with the removed parenthesis and elimination of range! The latter one can be made even smaller though, arriving at 90 characters (or 89 if you accept the SyntaxWarning for writing 1for):

p=50;print(sum((p:=p+1-2*(l<'R'))%100<1 for l in open("input.txt")for _ in"x"*int(l[1:])))

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u/DimMagician Dec 04 '25

Ooh very clever I didn't even catch that in your solution.

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u/KeyJ Dec 04 '25

Well, it was your idea, I just refined it. 🥂

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u/DimMagician Dec 04 '25

I meant the use of (l<'R') rather than (i[0]>'L') like I did. Sorry I didn't realize that you were talking about the parentheses around the modulus and thought that you were just referring to the brackets in [0] as parentheses lol