Roman Numerals: Step 12

We’re working on passing all cases up to 20.

Here’s the source:

static const std::string ToRoman(int n)
{
    std::string s;

    while (n >= 10) {
        n -= 10;
        s += "X";
    }

    if (n == 9) {
        n -= 9;
        s += "IX";
    }

    if (n >= 5) {
        n -= 5;
        s += "V";
    }

    if (n == 4) {
        n -= 4;
        s += "IV";
    }

    for (int i=0; i<n; ++i)
        s += "I";
    return s;
}

Merely changing the if to a while handles up to 20.

Now to refactoring: the repeated “X” is similar to the repeated “I”. Let’s refactor those so that they look identical.

Once that refactoring’s done, click Next.