Fibonacci with Memoization

/*
 * Problem : Fibonacci.
 * Input   : One integer n.
 * Output  : F(n).
 * Approach: Recursion with memo.
 * Time    : O(n)
 * Space   : O(n)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
        // Step 1: memo[i] stores F(i) after we compute it. 0 means "not computed yet" (F(i) is never 0 for i >= 1).
        static long fibonacci(int n, long[] memo) {
            // Step 2: Base cases.
            if (n < 2) {
                return n;
            }

            // Step 3: If we have the answer, use it. Otherwise compute it once and save it.
            if (memo[n] == 0) {
                memo[n] = fibonacci(n - 1, memo) + fibonacci(n - 2, memo);
            }
            return memo[n];
        }

    // This method solves the task. It receives the input and returns the answer.
    static long solve(long n) {
        return fibonacci((int) n, new long[(int) n + 2]);
    }

    public static void main(String[] args) {
        long n = new Scanner(System.in).nextLong();
        System.out.println(solve(n));
    }
}