Roman to Integer

这道题我是按定义来做的
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 package com.gxf.test;
 2 
 3 public class Solution {
 4     public int romanToInt(String s) {
 5         int result = 0;
 6         char array[] = s.toCharArray();
 7         int i = 0;
 8 
 9         while (i < array.length) {
10             switch (array[i]) {
11             case 'M':// 千位
12                 while (i < array.length && array[i] == 'M') {
13                     result += 1000;
14                     i++;
15                 }
16                 break;
17             case 'C':// 百位
18                 while (i < array.length && array[i] == 'C') {
19                     result += 100;
20                     i++;
21                 }
22                 if (i < array.length && array[i] == 'D') {
23                     result += 300;// 前面加过100
24                     i++;
25                 }// CD
26                 if (i < array.length && array[i] == 'M') {
27                     result += 800;// 前面加过100
28                     i++;
29                 }// CM
30                 break;
31             case 'D':// 百位500
32                 i++;
33                 result += 500;
34                 while (i < array.length && array[i] == 'C') {
35                     result += 100;
36                     i++;
37                 }
38                 break;
39             case 'X':// 十位
40                 while (i < array.length && array[i] == 'X') {
41                     result += 10;
42                     i++;
43                 }
44                 if (i < array.length && array[i] == 'L') {
45                     result += 30;
46                     i++;
47                 }
48                 if (i < array.length && array[i] == 'C') {
49                     result += 80;
50                     i++;
51                 }
52                 break;
53             case 'L':
54                 i++;
55                 result += 50;
56                 while (i < array.length && array[i] == 'X') {
57                     result += 10;
58                     i++;
59                 }// 十位
60                 break;
61             case 'I':// 个位
62                 while (i < array.length && array[i] == 'I') {
63                     result += 1;
64                     i++;
65                 }
66                 if (i < array.length && array[i] == 'V') {
67                     result += 3;
68                     i++;
69                 }
70                 if (i < array.length && array[i] == 'X') {
71                     result += 8;
72                     i++;
73                 }
74                 break;
75             case 'V':
76                 result += 5;
77                 i++;
78                 while (i < array.length && array[i] == 'I') {
79                     result += 1;
80                     i++;
81                 }
82             }
83         }
84 
85         return result;
86     }
87 
88 }