找出斐波那契数

public static long fibonacci(long index) {

if (index == 0) {
return 0;
}
else if (index == 1) {
return 1;
}
else {
return fibonacci(index - 1) + fibonacci(index - 2);
}
}

public static long fib(long index) {

int fib0 = 0;
int fib1 = 1;
int fib2 = 1;
if (index == 0) {
return fib0;
}
else if (index == 1) {
return fib1;
}
else if (index == 2) {
return fib2;
}
else {
for (int i = 3; i <= index; i++) {
fib0 = fib1;
fib1 = fib2;
fib2 = fib0 + fib1;
}
return fib2;
}
}