[LeetCode]Roman to Integer

题目描述:(链接)

Given a roman numeral, convert it to an integer.

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

解题思路:

 1 class Solution {
 2 public:
 3     int romanToInt(string s) {
 4         int len = s.size();
 5         if (len < 1) return 0;
 6         
 7         int result = 0;
 8         int sub = getRomanValue(s[0]);
 9         int lastV = sub;
10         for (int i = 1; i < len; ++i) {
11             char curC = s[i];
12             int curV = getRomanValue(curC);
13             if (curV == lastV) {
14                 sub += curV;
15             } else if (curV < lastV) {
16                 result += sub;
17                 sub = curV;
18             } else {
19                 sub = curV - lastV;
20             }
21             lastV = curV;
22         }
23         
24         result += sub;
25         return result;
26     }
27 private:
28     int getRomanValue(char c) {
29         switch(c) {
30             case 'I': return 1; 
31             case 'V': return 5;
32             case 'X': return 10;
33             case 'L': return 50;
34             case 'C': return 100;
35             case 'D': return 500;
36             case 'M': return 1000;
37             default: return 0;
38         }
39     }
40 };