【Leetcode】Roman to Integer

题目链接：https://leetcode.com/problems/roman-to-integer/

题目：

Given a roman numeral, convert it to an integer.

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

思路：

easy

算法：

 public int romanToInt(String s) {
     int pre, cur, sum;
     sum = charToInt(s.charAt(0));
     for (int i = 1; i < s.length(); i++) {
         pre = charToInt(s.charAt(i - 1));
         cur = charToInt(s.charAt(i));
         if (cur <= pre) {
             sum += cur;
         } else {
             sum = sum - 2 * pre + cur;
         }
     }
     return sum;
 }

 public static int charToInt(char c) {
     int data = 0;
     switch (c) {
     case 'I':
         data = 1;
         break;
     case 'V':
         data = 5;
         break;
     case 'X':
         data = 10;
         break;
     case 'L':
         data = 50;
         break;
     case 'C':
         data = 100;
         break;
     case 'D':
         data = 500;
         break;
     case 'M':
         data = 1000;
         break;
     }
     return data;
 }