LeetCode题目：Roman to Integer

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题目描述：

Given a roman numeral, convert it to an integer.

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

代码：

class Solution {public:    int romanToInt(string s) {    unordered_map<char, int> T = { { 'I' , 1 },                                   { 'V' , 5 },                                   { 'X' , 10 },                                   { 'L' , 50 },                                   { 'C' , 100 },                                   { 'D' , 500 },                                   { 'M' , 1000 }              };                                      int sum = T[s.back()];   for (int i = s.length() - 2; i >= 0; --i)    {       if (T[s[i]] < T[s[i + 1]])       {           sum -= T[s[i]];       }       else       {           sum += T[s[i]];       }   }      return sum;   }};