Integer to Roman——相当于查表法

Given an integer, convert it to a roman numeral.

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

没认真想，看到一种方法，应该算是最简单的方法了吧

基础知识：

罗马数字是由字符I,V,X,L,C,D,M等等表示的，其中
I = 1;
V = 5;
X = 10;
L = 50;
C = 100;
D = 500;
M = 1000;
接下来应该是V开始的重复，但是上面要加一个横线，表示对应数字的1000倍。
个位应该是：I,II,III,IV,V,VI,VII,VIII,IX
十位应该是：X,XX,XXX,XL,L,LX,LXX,LXXX,XC
百位应该是：C,CC,CCC,CD,D,DC,DCC,DCCC,CM

class Solution {
public:
    string intToRoman(int num) {
         char c[10][10][10]={{"0","I","II","III","IV","V","VI","VII","VIII","IX"},{"0","X","XX","XXX","XL","L","LX"
        ,"LXX","LXXX","XC"},{"0","C","CC","CCC","CD","D",
              "DC","DCC","DCCC","CM"},{"0","M","MM","MMM"}};
        int t=1;
        int tmp=num;
        string st;
        if(tmp/1000!=0) st+=c[3][tmp/1000];
        if((tmp%1000)/100!=0) st+=c[2][(tmp%1000)/100];
        if((tmp%100)/10!=0) st+=c[1][(tmp%100)/10];
        if(tmp%10!=0) st+=c[0][tmp%10];
        return st;
        
    }
};