C :

#include <stdio.h>
#include <string.h>
int main()
{
	int n,value,i,sum;
	char a[1001],temp;
	int tab[26]; 
	scanf("%d",&n);
	tab['I'] = 1;
    tab['V'] = 5;
    tab['X'] = 10;
    tab['L'] = 50;
    tab['C'] = 100;
    tab['D'] = 500;
    tab['M'] = 1000;
	while(n--)
	{
		scanf("%s",a);
		sum=0;
		for(i=0;i<strlen(a);i++)
		{
			value=tab[a[i]];
			temp=a[i+1];
			if((temp=='\n')||(temp=='\0')||(tab[temp]<=value))
			{
				sum+=value;
			}
			else
			{
				sum-=value;
			} 
		}
		printf("%d\n",sum); 
	}
	return 0;
 } 

C++ :

#include <string>
#include <iostream>
using namespace std;
int main()
{
	static int arab[] = {1,5,10,50,100,500,1000};
	static char rome[] = {'I','V','X','L','C','D','M'};
	string s[100];//n<100
	int dec[100],n,i,j;
	cin>>n;
	for(int k=0;k<n;k++)
	{
		cin>>s[k];
		int sum=0,former=0;//总和、当前数左边的数
		for(i=0;i<s[k].length();i++)
		{
			for(j=0;j<7;j++)
			{
				if(s[k][i]==rome[j])
				{
					if(arab[j]>former&&former)//当前数如果大于左边的
						former=-former;
					sum+=former;
					former=arab[j];
					if(i==s[k].length()-1)
						sum+=former;
				}
			}
		}
		dec[k]=sum;
	}
	for(i=0;i<n;i++) cout<<dec[i]<<endl;
	return 0;
}

Java :

import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner in = new Scanner(System.in);
		Scanner in1 = new Scanner(System.in);
		int n = in.nextInt();
		for (int i = 0; i < n; i++) {
			String s = in.next();
			int[] a = new int[s.length() + 1];
			for (int j = 0; j < s.length(); j++) {
				a[j] = lm(s.charAt(j));

			}
			//System.out.println(a[2]);
			int sum = 0;
			for (int x = s.length() - 1; x >= 0; x--) {
				if (sum > a[x] && a[x] != a[x + 1]) {

					sum = sum - a[x];
				} else {
					// System.out.println("111");
					sum += a[x];
					// System.out.println(x);
				}
				// System.out.println(sum);
				// System.out.println(a[x]);
			}
			// if(sum>a[0])
			// System.out.println(sum-a[0]);
			// else
			System.out.println(sum);
		}

	}

	static int lm(char c) {
		switch (c) {
		case 'I':
			return 1;
		case 'V':
			return 5;
		case 'X':
			return 10;
		case 'C':
			return 100;

		case 'L':
			return 50;
		case 'D':
			return 500;
		case 'M':
			return 1000;
		default:
			break;
		}

		return 1;

	}
}