project-euler/Sidef/025 1000-digit Fibonacci number.sf

#!/usr/bin/ruby

# Author: Daniel "Trizen" Șuteu
# License: GPLv3
# Website: https://github.com/trizen

# What is the index of the first term in the Fibonacci sequence to contain 1000 digits?

# https://projecteuler.net/problem=25

# Runtime: 0.163s

func fib_n_digits(n) {
    var (f1, f2) = (1, 1);

    var i = 2;
    loop {
        (f1, f2) = (f2, f1+f2)
        if (f2.length == n) {
            return i+1;
        }
        ++i
    }
}

say fib_n_digits(1000);