a013: 羅馬數字 FYI: https://yunlinsong.blogspot.com/2016/02/blog-post_1.html

a013.cpp

#include <iostream>

using namespace std;

short number(char c)
{
    short num;

    switch(c)
    {
        case 'I':
            num =  1;
            break;

        case 'V':
            num = 5;
            break;

        case 'X':
            num = 10;
            break;

        case 'L':
            num = 50;
            break;

        case 'C':
            num = 100;
            break;

        case 'D':
            num = 500;
            break;

        case 'M':
            num = 1000;
            break;

        default:
            num = 0;
            break;
    }

    return num;
}

short getValue(const string& s )
{
        short preValue = 1000, curValue, value = 0;
        short len = s.length();

        for( int i = 0; i < len; i++ )
        {
            curValue = number(s[i]);
            value += curValue;

            if( curValue > preValue )
                value -= 2 * preValue;

            preValue = curValue;
        }

        return value;
}

void attachMsg(short check, string &result, string msg)
{
    if( check == 9 )
    {
        result.append(msg.substr(2,1));
        result.append(msg.substr(0,1));

        check = 0;
    }

    if( check == 4 )
    {
        result.append(msg.substr(2,1));
        result.append(msg.substr(1,1));

        check = 0;
    }

    if( check >= 5 )
    {
        result.append(msg.substr(1,1));
        check -= 5;
    }

    for(int i = 0; i < check; i++)
    {
        result.append(msg.substr(2,1));
    }
}

void prtNum( short n )
{
    string result;
    n = (n < 0 ? -n: n);

    short check = n / 1000;
    for(int i = 0; i < check; i++)
        result.append("M");

    n = n % 1000;
    check = n / 100;
    attachMsg(check, result, "MDC");

    n = n % 100;
    check = n / 10;
    attachMsg(check, result, "CLX");

    n = n % 10;
    check = n;
    attachMsg(check, result, "XVI");

    cout << result;
}

int main()
{
    string a, b;
    short numA, numB, numDif;



    while( cin >> a )
    {
        if( a[0] == '#' )
            break;

        cin >> b;

        numA = getValue(a);
        numB = getValue(b);

        numDif = numA - numB;

        if( numDif != 0 )
            prtNum(numDif);
        else
            cout << "ZERO";

        cout << endl;
    }

    return 0;
}