AlgoDesignAndTechniqueEdxJava/sources/Fibonacci.java


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import java.util.Scanner;

public class Fibonacci {
	public static long fib_naive(int n) {
		if (n <= 1)
			return n;

		return fib_naive(n - 1) + fib_naive(n - 2);
	}

	public static long fib_optimized1(int i) {
		if (i <= 1)
			return (long) i;
		final long[] fibArray = new long[i+1];
		fibArray[0] = 0;
		fibArray[1] = 1;
		for (int j = 2; j < i+1; j++) {
			fibArray[j] = fibArray[j - 1] + fibArray[j - 2];
		}
		return fibArray[i];
	}

	public static void main(String args[]) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();

		System.out.println(fib_optimized1(n));
	}

}