leetcode Roman to integer

题目：
Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999.

要把罗马数字转换为整数， 罗马数字自行百度

code:

class Solution{  public:    int romanToInt(string s)    {       map<char,int> Roman;       Roman['I'] = 1;       Roman['V'] = 5;       Roman['X'] =10;       Roman['L'] =50;       Roman['C'] =100;       Roman['D'] =500;       Roman['M'] =1000;       int i=s.length()-1;       int res;       while(i>=0)       {          if(i==s.length()-1)          {            res=Roman[s[i]];            i--;          }          if(Roman[s[i]] >= Roman[s[i+1]])            res=res+Roman[s[i]];          else            res=res-Roman[s[i]];          i--;       }       return res;   }};