13.罗马数字转成整形 Roman to Integer

Given a roman numeral, convert it to an integer.

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


  1. public class Solution {
  2.     public int RomanCharToInt(char c)
  3.     {
  4.         switch (c)
  5.         {
  6.             case 'I':
  7.                 return 1;
  8.             case 'V':
  9.                 return 5;
  10.             case 'X':
  11.                 return 10;
  12.             case 'L':
  13.                 return 50;
  14.             case 'C':
  15.                 return 100;
  16.             case 'D':
  17.                 return 500;
  18.             case 'M':
  19.                 return 1000;
  20.             default:
  21.                 return 0;
  22.         }
  23.     }
  25.     public int RomanToInt(string s)
  26.     {
  27.         int length = s.Length;
  28.         int i = length - 1;
  29.         int sum = RomanCharToInt(s[i--]);
  30.         while (i >= 0)
  31.         {
  32.             if (RomanCharToInt(s[i + 1]) > RomanCharToInt(s[i]))
  33.             {
  34.                 sum -= RomanCharToInt(s[i--]);
  35.             }
  36.             else
  37.             {
  38.                 sum += RomanCharToInt(s[i--]);
  39.             }
  40.         }
  41.         return sum;
  42.     }
  43. }





posted @ 2017-01-10 23:21  xiejunzhao  阅读(240)  评论(0)    收藏  举报