Fibonacci Number Problem & Solution
The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1.
That is,
F(0) = 0, F(1) = 1
F(n) = F(n - 1) + F(n - 2), for n > 1.Given n, calculate F(n).
See the fibonacci number problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
class Solution {
public:
int fib(int n) {
if (n == 0) {
return 0;
} else if (n == 1) {
return 1;
} else {
int first = 0;
int second = 1;
for (int i = 2; i <= n; ++i) {
int tmp = first + second;
first = second;
second = tmp;
}
return second;
}
}
};