Let's define digit degree of some positive integer as the number of times we need to replace this number with the sum of its digits until we get to a one digit number. Given an integer, find its digit degree.

function digitDegree(n: number): number {
    let current = n;
    let count = 0;

    if (n <= 9) {
        return count;
    }

    while (current > 9) {
        count++;
        current = getDigit(current);
    }

    return count;
}

function getDigit(num: number): number {
    let arr = num.toString().split('');
    let sum = 0;
    for (let i = 0; i < arr.length; i++) {
        sum += Number(arr[i]);
    }
    return sum;
}