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.
public class Solution {
public int Fib(int N) {
int f1 = 0;
int f2 = 1;
int sum = 1;
if(N==0){
return f1;
}
for(int i=2;i<=N;i++){
sum=f1+f2;
f1=f2;
f2=sum;
}
return sum;
}
}Time Complexity: O(n)
Space Complexity: O(1)
