Roman to Integer

Given a roman numeral, convert it to an integer.

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

 

AC最快的一次。。每种字母代表一个数字。小的在左边表示右减左，小的在右边表示右加左。如IV表示4， VI表示6.

I, i: 1

V, v: 5

X, x: 10

L, l: 50

C, c: 100

D, d: 500

M, m: 1000

 1 class Solution {
 2 public:
 3     int romanToInt(string s) {
 4         int times = 1;
 5         int result = 0;
 6         for(int i = 0; i < s.length() - 1; i++){
 7             if(toint(s[i]) == toint(s[i+1])) times++;
 8             else if(toint(s[i+1]) > toint(s[i])){
 9                 result -= toint(s[i]) * times;
10                 times = 1;
11             }
12             else{
13                 result += toint(s[i]) * times;
14                 times = 1;
15             }
16         }
17         result += toint(s[s.length()-1]) * times;
18         return result;
19     }
20     int toint(char ch){
21         switch(ch){
22             case 'I': case 'i': return 1;
23             case 'V': case 'v': return 5;
24             case 'X': case 'x': return 10;
25             case 'L': case 'l': return 50;
26             case 'C': case 'c': return 100;
27             case 'D': case 'd': return 500;
28             case 'M': case 'm': return 1000;
29         }
30     }
31 };

 

posted @ 2015-04-12 15:09  amazingzoe  阅读(87)  评论(0)  编辑  收藏  举报