题解 | 牛牛学数列5

#include<bits/stdc++.h>
using namespace std;
int fibonacci(int n){
	if(n<=0) return 0;
	if(n==1) return 1;
	int a =0,b=1,c;
	for(int i=2;i<=n;i++){
		c = a+b;
		a = b;
		b = c;
	}
	return b;
}
int main(){
	int n;
	cin>>n;
	cout<<fibonacci(n)<<endl;
	return 0;
}