poj 2081 Recaman's Sequence (dp)

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        int n = 0;
        int[] result;
        boolean[] marked = new boolean[10000000];
        while((n = sc.nextInt()) != -1) {
            result = new int[n + 1];
            for(int i = 1; i < n + 1; i++) {
                int a = result[i - 1] - i;
                if(a > 0 && !marked[a]) {
                    result[i] = a;
                    marked[a] = true;
                }
                else {
                    result[i] = a + 2 * i;
                    marked[a + 2 * i] = true;
                }
            }
            System.out.println(result[n]);
            for(int i = 0; i < 10000000; i++ )
                marked[i] = false;
         }
    }
}