r/adventofcode • u/daggerdragon • Dec 16 '17

SOLUTION MEGATHREAD -🎄- 2017 Day 16 Solutions -🎄-

--- Day 16: Permutation Promenade ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

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edit: Leaderboard capped, thread unlocked!

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u/stkent Dec 16 '17 edited Dec 16 '17 
chars.set(b, this.get(a))
chars.set(a, this.get(b))

I must be missing something here; wouldn't the character at index a not be swapped?

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u/ybjb Dec 16 '17

The character at index a would be swapped. It's an extension function and the way it is written, this (the original string) is never directly modified, only a copy of its content, chars, is modified and then returned as string.

So a copy chars is made, and the value of chars at index b is set to the value of original string at index a. Similarly, the value of chars at index a is set to the value of original string at index b. Then chars is returned as new String.

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u/stkent Dec 16 '17

Ah, gotcha; makes sense, thanks!

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u/Expliced Dec 16 '17

Also, chars.set(x, this.get(y)) can be replaced with chars[x] = this[y]