Integer to Roman

题目

Given an integer, convert it to a roman numeral.

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

解题思路

从低位到高位分解数的每一位，然后用罗马字符串表示该位上的数，需要注意的是每次都从串头插入。

因为输入数据的取值范围很小，所以可以把每位上9个数的罗马串提前存起来。

代码

public class Solution {

public String intToRoman(int num)
{
String[][] table ={{"I","II","III","IV","V","VI","VII","VIII","IX"},
{"X","XX","XXX","XL","L","LX","LXX","LXXX","XC"},
{"C","CC","CCC","CD","D","DC","DCC","DCCC","CM"},
{"M","MM","MMM"}};
StringBuffer sb=new StringBuffer();
int n;

for(int i=0;num!=0;num/=10,++i)
{
n=num%10;
if(n!=0)
sb.insert(0,table[i][n-1]);
}
return sb.toString();
}
}

运行结果