试题:将罗马数字转为阿拉伯数字

#include <cstdio>#include <cassert>#include <iomanip>#include <list>#include <iterator>#include <string>#include <iostream>using namespace std;void Arabic2Roman(int arabic, list<char> & roman){    ......}struct Exception{};int Alpha2Bit(char alpha){    switch (alpha)    {        case 'I':        {            return 0;        }        case 'V':        {            return 1;        }        case 'X':        {            return 2;        }        case 'L':        {            return 3;        }        case 'C':        {            return 4;        }        case 'D':        {            return 5;        }        case 'M':        {            return 6;        }        default:        {            throw Exception();            return -1;        }    }}int Roman2Arabic(const list<char> & roman){    static int const base[] =    {        1, 10, 100, 1000    };    int arabic = 0;    int lastbit = 7;    list<char>::const_reverse_iterator iter = roman.rbegin();    while (iter != roman.rend())    {        int bit = Alpha2Bit(*iter);        if (bit >= lastbit)        {            throw Exception();            return -1;        }        int factor = 0;        if (0 == bit % 2)        {            list<char>::const_reverse_iterator tmpiter = iter;            ++tmpiter;            if (tmpiter != roman.rend())            {                switch (Alpha2Bit(*tmpiter) - bit)                {                    case 0:                    {                        factor = 2;                        iter = tmpiter;                        ++tmpiter;                        if (tmpiter != roman.rend() && Alpha2Bit((*tmpiter)) == bit)                        {                            ++factor;                            iter = tmpiter;                        }                        break;                    }                    case 1:                    {                        factor = 4;                        iter = tmpiter;                        break;                    }                    case 2:                    {                        factor = 9;                        iter = tmpiter;                        break;                    }                    default:                    {                        factor = 1;                        break;                    }                }            }            else            {                factor = 1;            }            lastbit = bit;        }        else        {            factor = 5;            list<char>::const_reverse_iterator tmpiter = iter;            ++tmpiter;            while (tmpiter != roman.rend() && Alpha2Bit(*tmpiter) == bit - 1 && factor < 8)            {                ++factor;                iter = tmpiter;                ++tmpiter;            }            lastbit = bit - 1;        }        arabic += factor * base[lastbit / 2];        ++iter;    }    if (0 == arabic)    {        throw Exception();        return -1;    }    else    {        return arabic;    }}int main(){    for (int i = 1; i < 4000; ++i)    {        try        {            list<char> roman;            Arabic2Roman(i, roman);            int arabic = Roman2Arabic(roman);            if (arabic != i)            {                cout << "error conversion : " << endl << '\t';            }            cout << setw(4) << i << " -> ";            for (list<char>::reverse_iterator iter = roman.rbegin(); iter != roman.rend();)            {                cout << (*iter);                ++iter;            }            cout << " -> " << arabic << endl;            if (arabic != i)            {                cin.get();            }        }        catch (Exception & e)        {            cout << "converse " << i << " throw exception" << endl;            cin.get();        }    }    cout << "input roman number:";    string alpha;    while (cin >> alpha)    {        list<char> roman;        for (string::reverse_iterator iter = alpha.rbegin(); iter != alpha.rend(); ++iter)        {            roman.push_back(*iter);        }        try        {            int arabic = Roman2Arabic(roman);            cout << '\t' << arabic << endl;        }        catch (Exception & e)        {            cout << '\t' << "can not converse " << alpha << endl;        }    }    return 0;}

其中Arabic2Roman()在 试题:将阿拉伯数字转为罗马数字 中有给出实现代码