Given an integer, convert it to a roman numeral.

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

https://oj.leetcode.com/problems/integer-to-roman/

思路1：构造法，每一位构造然后拼接。每一位表示的字母虽然不同，但是规则是一样的，所以考虑每一位上0-9的表现形式，然后拼接起来。（详见参考1）

思路2：采用贪心策略，每次选择能表示的最大的值，把对应的字符串连接起来，代码及其简洁。

贪心：

public class Solution {    public String intToRoman(int num) {        String[] str = new String[] { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" };        int[] val = new int[] { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };        StringBuilder sb = new StringBuilder();        for (int i = 0; num > 0; i++) {                        while (num >= val[i]) {                num -= val[i];                sb.append(str[i]);            }        }        return sb.toString();    }        public static void main(String[]args){        System.out.println(new Solution().intToRoman(999));    }}

参考：

http://www.cnblogs.com/zhaolizhen/p/romannumber.html

http://blog.csdn.net/havenoidea/article/details/11848921