Integer to Roman.cpp

class Solution {
public:
    string intToRoman(int num) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function    
        string result="";
        if(num>=1000) result+=string(num/1000, 'M');
        num=num%1000; result+=stringHelper(num/100, "C", "D", "M");
        num=num%100;  result+=stringHelper(num/10, "X", "L", "C");
        num=num%10;   result+=stringHelper(num, "I", "V", "X");
        return result; 
    }
    string stringHelper(int num, string one, string five, string ten)
    {
        string result=""; 
        switch(num)
        {
            case 1: case 2: case 3: 
            return string(num, one[0]); 
            case 4:
            return one+five; 
            case 5: 
            return five; 
            case 6: case 7: case 8:
            return five+string(num-5, one[0]); 
            case 9: 
            return one+ten;
        }
        return result; 
    }
};

Integer to Roman.java

public class Solution {
    public String intToRoman(int num) {
        StringBuffer sb=new StringBuffer(); 
        while(num>=900)
        {
           if(num>=900 && num<1000)
          {
            sb.append("C");
            num+=100; 
          }
          while(num>=1000)
          {
            sb.append("M");
            num-=1000; 
          }
        }
        while(num<900&&num>=90)
        {
          if(num>=500)
          {
            num-=500; 
            sb.append("D"); 
          }else if(num>=400)
          {
            num+=100; 
            sb.append("C"); 
            continue; 
          }
           if(num>=90&& num<100)
          {
            num+=10; 
            sb.append("X");
          }        
          while(num>=100)
          {
            num-=100; 
            sb.append("C");
          }
        }
        while(num>=9 && num<90)
        {
          if(num>=50)
          {
            num-=50; 
            sb.append("L");
          }else if(num>=40)
          {
            num+=10; 
            sb.append("X");
            continue; 
          }
            if(num==9) 
          {
            num+=1; 
            sb.append("I");
          }
          while(num>=10)
          {
            num-=10; 
            sb.append("X");
          }
        }
        while(num>=1 && num<9)
        {
          if(num==4)
          {
            num+=1; 
            sb.append("I");
          }
          if(num>=5)
          {
            num-=5; 
            sb.append("V");
          }
          while(num>=1)
          {
            num-=1; 
            sb.append("I");
          }
          }
          return sb.toString(); 
        }
}