class Solution {
public:
int Fibonacci(int n) {
if(n <= 0)
return 0;
if(n == 1)
return 1;
long long int F0 = 0;
long long int F1 = 1;
long long int FN = 0;
for(int i = 2; i <= n; i++){
FN = F0 + F1;
F0 = F1;
F1 = FN;
}
return FN;
}
};
符合时间复杂度。