13. Roman to Integer

Given a roman numeral, convert it to an integer.

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

 

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把罗马数字转成阿拉伯整数

 

C++（85ms）：

 1 class Solution {
 2 public:
 3     int romanToInt(string s) {
 4         unordered_map<char,int> m ={{'I',1},
 5                                     {'V',5},
 6                                     {'X',10},
 7                                     {'L',50},
 8                                     {'C',100},
 9                                     {'D',500},
10                                     {'M',1000},};
11 
12         int sum = m[s.back()] ;
13         for (int i = s.size()-2; i >= 0;i-- ){
14             if (m[s[i]] < m[s[i+1]])
15                 sum -= m[s[i]] ;
16             else
17                 sum += m[s[i]] ;
18         }
19         return sum ;
20     }
21 };

 

posted @ 2017-03-17 16:12  __Meng  阅读(127)  评论(0)  编辑  收藏  举报