>>506
再帰

int fib(int n) {
if (n == 0) return 0;
else if (n == 1) return 1;
else return fib(n-1) + fib(n-2);
}

非再帰

int fib(int n) {
int a = 0;
int b = 1;
while (n > 0) {
int t = a+b;
a = b;
b = t;
n = n-1;
}
return a;
}