题目
十二题.png
题目十分简单，就是将阿拉伯数字转换为罗马数字。此题的要点在于理解罗马数字的表示规则。而该规则在百度百科说的十分清楚（罗马数字）
分析
明白了罗马数字的表示规则之后，此题就很简单了。并且由题目可知最大为3999。这就意味着可以用一个二维数组将所有的情况简单的列出来，如下所示：
String[][] nn={{"","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"}};
分别对应个位的1-9，十位的10-90，百位的100-900，千位的1000-3000。然后根据求得的值从数组中取得相应的值来连接字符串，生成结果。如1204,1204/1000=1，取出对应的“M”；204/100=2,2取出对应的“CC“；0/10=0,取出对应的“”;4/1=4,取出对应的“IV“。然后将这几个字符串连接起来即是结果：“MCCIV”。
代码
代码为Java版，如下：
public class Solution
{
public String intToRoman(int num)
{
String[][] nn={{"","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"}};
int temp=num/1000;
String result=nn[3][temp];
num-=temp*1000;
temp=num/100;
result+=nn[2][temp];
num-=temp*100;
temp=num/10;
result+=nn[1][temp];
num-=temp*10;
temp=num;
result+=nn[0][temp];
return result;
}
}