509. 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



Solution : 
//Java 

class Solution {
    public int fib(int n) {
        if(n==0){
            return 0;
        }
        if(n==1){
            return 1;
        }
        int arr[]=new int[n+1];
        arr[0]=0;
        arr[1]=1;
        for(int i=2;i<=n;i++){
            arr[i]=arr[i-1]+arr[i-2];
        }
            return arr[n];
    }
}


Solution 2:
//Java
import java.util.*;
public class Fibonacci {
    public static void main(String[] args) {
        Scanner a=new Scanner(System.in);
        int n = a.nextInt(); // Number of terms to print

        int first = 0, second = 1;
        System.out.print("Fibonacci Series up to " + n + " terms: ");

        for (int i = 0; i <= n; i++) {
            System.out.print(first + " ");

            int next = first + second;
            first = second;
            second = next;
        }
    }
}