Roman to Integer

Problem

Convert a valid Roman numeral string to its integer value.

Add each symbol's value, except when a smaller symbol precedes a larger one, in which case subtract the smaller value, as in IV = 4 and IX = 9. Assume s is a valid numeral between 1 and 3999.

Hint

Only the subtractive pairs put a smaller symbol before a larger one.

Test cases

case 1

in: ["III"]

expected: 3

case 2

in: ["IV"]

expected: 4

case 3

in: ["MCMXCIV"]

expected: 1994

case 4

in: ["LVIII"]

expected: 58

case 5

in: ["IX"]

expected: 9

Starter codePython

def roman_to_int(s):
    # Your code here
    pass

5 test cases · run your code against them in the editor