feat: update sum to cube

[suiwater]

pub fn is_armstrong_number(mut num: u128) -> bool {
    let original_num = num;
    let mut sum = 0;
    let digits = count_digits_of_base(num, 10);
    loop {
        if num == 0 {
            break original_num == sum;
        }

        let lastDigit = num % 10;
        let sum = sum + pow(lastDigit, digits);
        num = num / 10;
        if sum > original_num {
            break false;
        }
    }
}

The original code may have been like this, so using variable sum is not suitable now

[github-actions]

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[github-actions]

There hasn't been any activity on this pull request recently, and in order to prioritize active work, it has been marked as stale.
This PR will be closed and locked in 7 days if no further activity occurs.
Thank you for your contributions!