[LeetCode] Integer to Roman 解题报告

Given an integer, convert it to a roman numeral.

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

» Solve this problem

[解题思路]
这道题主要就在于如何处理每一位digit，并且按照区间不同处理：
1<=digit <=3
digit =4
digit = 5
5<digit<=8
digit =9

[Code]

1:  string intToRoman(int num) {  
2:      // Start typing your C/C++ solution below  
3:      // DO NOT write int main() function    
4:      char symbol[7] = { 'I','V','X', 'L','C', 'D','M'};  
5:      string roman;  
6:      int scale = 1000;  
7:      for(int i =6; i>=0; i-=2)  
8:      {  
9:        int digit = num/scale;  
10:        if(digit != 0)  
11:        {        
12:          if(digit <= 3)  
13:          {  
14:            roman.append(digit, symbol[i]);  
15:          }  
16:          else if(digit ==4)  
17:          {  
18:            roman.append(1, symbol[i]);  
19:            roman.append(1, symbol[i+1]);  
20:          }  
21:          else if(digit ==5)  
22:          {  
23:            roman.append(1, symbol[i+1]);  
24:          }  
25:          else if(digit <=8)  
26:          {  
27:            roman.append(1, symbol[i+1]);  
28:            roman.append(digit-5, symbol[i]);  
29:          }  
30:          else if(digit ==9)  
31:          {  
32:            roman.append(1, symbol[i]);  
33:            roman.append(1, symbol[i+2]);  
34:          }  
35:        }  
36:        num = num%scale;  
37:        scale/=10;        
38:      }  
39:      return roman;  
40:    }