Problem S2: Aromatic Numbers

Problem DescriptionCopy Anchor Link

This question involves calculating the value of aromatic numbers which are a combination of Arabic digits and Roman numerals.

An aromatic number is of the form $ARARAR \ldots AR$, where each $A$ is an Arabic digit, and each $R$ is a Roman numeral. Each pair $AR$ contributes a value described below, and by adding or subtracting these values together we get the value of the entire aromatic number.

An Arabic digit $A$ can be 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9. A Roman numeral $R$ is one of the seven letters I, V, X, L, C, D, or M. Each Roman numeral has a base value:

The value of a pair $AR$ is $A$ times the base value of $R$. Normally, you add up the values of the pairs to get the overall value. However, wherever there are consecutive symbols $ARA'R'$ with $R'$ having a strictly bigger base value than $R,$ the value of pair $AR$ must be subtracted from the total, instead of being added.

For example, the number 3M1D2C has the value $3*1000+1*500+2*100 = 3700$ and 3X2I4X has the value $3*10-2*1+4*10=68$.

Write a program that computes the values of aromatic numbers.

Input SpecificationCopy Anchor Link

The input is a valid aromatic number consisting of between 2 and 20 symbols.

Output SpecificationCopy Anchor Link

The output is the decimal value of the given aromatic number.

Sample Input 1Copy Anchor Link

3M1D2C

Output for Sample Input 1Copy Anchor Link

3700

Sample Input 2Copy Anchor Link

2I3I2X9V1X

Output for Sample Input 2Copy Anchor Link

-16