LeetCode Problem : Integer to Roman

Problem

Given an integer, convert it to a roman numeral.

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

Code

string itor(int i,char one,char five,char ten){
    string result;
    if(i < 4){
        for(int j = 0;j < i;++j)
            result += one;
    }
    else if(i == 4){
        result += one;
        result += five; 
    }
    else if(i < 9){
        result += five;
        for(int j = 0;j < i - 5;++j)
            result += one;
    }
    else{
        result += one;
        result += ten;
    }
    return result;
}
string intToRoman(int num) {
    // Note: The Solution object is instantiated only once and is reused by each test case.    
    string result;
    result += itor((num/1000)%10,'M','O','O');
    result += itor((num/100)%10,'C','D','M');
    result += itor((num/10)%10,'X','L','C');
    result += itor(num%10,'I','V','X');
    return result;   
}