Description:
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: 2
Output: 1
Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.
Example 2:
Input: 3
Output: 2
Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.
Example 3:
Input: 4
Output: 3
Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.
Note:
- 0 ≤ N ≤ 30.
Java
class Solution {
public int fib(int N) {
if (N == 0) return 0;
if (N == 1) return 1;
int f1 = 0;
int f2 = 1;
for (int i = 2; i <= N; i++) {
int temp = f2;
f2 = f1 + f2;
f1 = temp;
}
return f2;
}
}