Project Euler: Problem 25

The Fibonacci sequence is defined by the recurrence relation:

F_n = F_n−1 + F_n−2 , where F₁ = 1 and F₂ = 1.

Hence the first 12 terms will be:

F₁ = 1
F₂ = 1
F₃ = 2
F₄ = 3
F₅ = 5
F₆ = 8
F₇ = 13
F₈ = 21
F₉ = 34
F₁₀ = 55
F₁₁ = 89
F₁₂ = 144

The 12th term, F₁₂ , is the first term to contain three digits.

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

BigInteger number1 = BigInteger.ZERO;
BigInteger number2 = BigInteger.ONE;
BigInteger temp = BigInteger.ZERO;
int count = 1;
 
while (number2.toString().length()<1000) {
	temp = number1.add(number2);
	number1 = number2;
	number2 = temp;
	count++;
}
System.out.println(count);

Lösung: 4782