Fibonacci Number
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)
.
Example 1:
Input: n = 2
Output: 1
Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.
Example 2:
Input: n = 3
Output: 2
Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.
Example 3:
Input: n = 4
Output: 3
Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.
Constraints:
0 <= n <= 30
Solutions
🧠 Cpp
class Solution
{
//max n == 30
array<int, 31> _storage = {0,1};
public:
constexpr int fib(int n)
{
if(n && !_storage[n])
_storage[n] = fib(n-1) + fib(n-2);
return _storage[n];
}
};
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