[LeetCode]Integer to Roman

class Solution {
//refer to http://discuss.leetcode.com/questions/194/integer-to-roman @Ark
//roman number
//I II III IV V VI VII VIII IX
//I 1
//V 5
//X 10
//L 50
//C 100
//D 500
//M 1000
public:
	string intToRoman(int num) {
		const static char* Roman = "IVXLCDM";
		string ret;
		for (int base = 0; num; num /= 10, base += 2) 
		{
			int x = num % 10;
			switch (x) 
			{
			case 1: case 2: case 3:
				ret = string(x, Roman[base]) + ret;
				break;
			case 4:
				ret = Roman[base+1] + ret;
				ret = Roman[base] + ret;
				break;
			case 5:
				ret = Roman[base+1] + ret;
				break;
			case 6: case 7: case 8:
				ret = string(x-5, Roman[base]) + ret;
				ret = Roman[base+1] + ret;
				break;
			case 9:
				ret = Roman[base+2] + ret;
				ret = Roman[base] + ret;
				break;
			default:
				break;
			}
		}
		return ret;
	}
};