LeetCode 13. Roman to Integer

Posted 2020-09-24 浩然

https://leetcode.com/problems/roman-to-integer/#/description

Given a roman numeral, convert it to an integer.

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

• 字符串简单题，要搞清楚转换规则。如果当前字母比前一个大，则相减，比如IV = 5 - 1；否则就相加，比如VI = 5 + 1，II = 1 + 1。
• 罗马数字_百度百科
  • http://baike.baidu.com/link?url=JBuRWsGjAmYIlIhaPN_ywmIJBMrTWT6iKb2-WhqyTA6RqitOQuqnvQ2PHVfelAf00iGWWtgTzUjB3W4YMR0XWLfadA6YVi_s2J1aUgb-n1eBewvqGmyRpdH3VsVVs4q3

 

 1 #include <iostream>
 2 #include <string>
 3 using namespace std;
 4 
 5 class Solution {
 6 public:
 7     inline int map(const char inCh)
 8     {
 9         switch (inCh)
10         {
11             case ‘I‘: return 1;
12             case ‘V‘: return 5;
13             case ‘X‘: return 10;
14             case ‘L‘: return 50;
15             case ‘C‘: return 100;
16             case ‘D‘: return 500;
17             case ‘M‘: return 1000;
18             default:    return 0;
19         }
20         
21     }
22     
23     int romanToInt(string s)
24     {
25         int result = 0;
26         
27         for (size_t i = 0; i < s.size(); i ++) {
28             if ((i > 0) && (map(s[i]) > map(s[i - 1]))) {
29                 result += map(s[i]) - 2 * map(s[i - 1]);
30             } else {
31                 result += map(s[i]);
32             }
33         }
34         
35         return result;
36     }
37 };
38 
39 int main ()
40 {
41     Solution testSolution;
42     string sTest[] = {"XXI", "XXIX"};
43 
44     for (int i = 0; i < 2; i ++)
45         cout << testSolution.romanToInt(sTest[i]) << endl;
46     
47     return 0;
48 }

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