freecodecamp--freecodecamp/curriculum/challenges/english/blocks/daily-coding-challenges-python/69f8c998d78ad3171a0713ba.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
69f8c998d78ad3171a0713ba	Challenge 287: Roman Numeral Fixer	29	challenge-287

--description--

Given a string of malformed Roman numerals, return the value in standard Roman numeral notation.

The input will only use additive notation, so each symbol adds its value to the total. As a reminder, here are the symbols and values:

Symbol	Value
"I"	1
"V"	5
"X"	10
"L"	50
"C"	100
"D"	500
"M"	1000

When re-encoding, use the largest possible symbol at each step, using subtractive pairs ("IV", "IX", "XL", "XC", "CD", "CM") where needed.

--hints--

fix_numerals("XIIIII") should return "XV".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(fix_numerals("XIIIII"), "XV")`)
}})

fix_numerals("IIIILX") should return "LXIV".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(fix_numerals("IIIILX"), "LXIV")`)
}})

fix_numerals("XXVVVIIIII") should return "XL".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(fix_numerals("XXVVVIIIII"), "XL")`)
}})

fix_numerals("MDCCLXXXXVIIII") should return "MDCCXCIX".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(fix_numerals("MDCCLXXXXVIIII"), "MDCCXCIX")`)
}})

fix_numerals("IIIIVVVVXXXXLLLLCCDD") should return "MCDLXIV".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(fix_numerals("IIIIVVVVXXXXLLLLCCDD"), "MCDLXIV")`)
}})

fix_numerals("ILCDMIVDIIXLCVCXDL") should return "MMCMLXXXIV".

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(fix_numerals("ILCDMIVDIIXLCVCXDL"), "MMCMLXXXIV")`)
}})

--seed--

--seed-contents--

def fix_numerals(s):

    return s

--solutions--

def fix_numerals(s):
    values = {"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}
    encoding = [
        (1000, "M"), (900, "CM"), (500, "D"), (400, "CD"),
        (100, "C"), (90, "XC"), (50, "L"), (40, "XL"),
        (10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I")
    ]

    total = sum(values[c] for c in s)

    result = ""
    for value, symbol in encoding:
        while total >= value:
            result += symbol
            total -= value
    return result