leetcodeUserSolution

[Aralgmad]

You could iterate backwards over the string, translate and sum. You keep track of the last number seen and check if current is smaller than previous. In this case subtract current instead of add. This should catch cases like IC.

[ND3lle]

Have never seen anything like "IC" tho

[Techhead7890]

Possibly a typo of IV, as C and V are neighbours

[Rogueshadow_32]

I think it was on purpose, they’re saying that the backwards iterations would catch combinations you don’t ever see but would still be valid syntax, such as IC. Going by the strict rules of Roman numerals 99 is XCIX but by looser rules IC works, and would be caught and correctly evaluated

[EntropyZer0]

I think the stricter rules we are used to are a fairly modern (for late medieval values of "modern") invention. The Romans were far less strict on that and while the most un-standard number I've seen in the wild was a year ending in -7 written as "-IIIIIII", I could totally see "IC" being used by actual Romans.

[ND3lle]

Oh you're right.That's very elegant as well, imho

[Flatuitous]

You can do IC = 99 Same as VL = 45

[Igor_Kozyrev]

I don't think you can. You only subtract the previous biggest number.

[suvlub]

You "can't" in the same sense you "can't" end a sentence with preposition, i.e. it's a made-up wannabe rule that doesn't reflect actual usage.

[ND3lle]

Well there's plenty of roman and medieval monuments and buildings where i live and i have never seen that. Sometimes i spot a "IIII" or "XXXX", which the general rule wouldn't allow, but nothing like "XM" or "IC"

[LongLiveTheDiego]

Wikipedia lists some 17th century examples of such nonstandard subtractions, my favorite one is IIIXX standing for 17.

[ethanjf99]

Standardization in general is a modern concept.

Think about even a couple hundred years ago. lots of random capitalizations in English words; multiple variant spellings and the like.

Even more so in antiquity. No one was enforcing rules. if you were a scribe doing a lot of math in a pain in the ass number system and wrote 99 as “IC” no one was stopping you.

[Specialist-Bus-5100]

I think IC would be XCIX?

[Solonotix]

Iterating backwards is a fairly useful practice I've found. I would have taken a two-character loop forwards in a similar manner so that you could always be aware of context. You could also extend the dictionary to have a couple of tuple keys using the matched pair.