poj 2081 Recaman's Sequence (dp)
Recaman's Sequence
Time Limit: 3000MS | Memory Limit: 60000K | |
Total Submissions: 22566 | Accepted: 9697 |
Description
The Recaman's sequence is defined by a0 = 0 ; for m > 0, am = am−1 − m if the rsulting am is positive and not already in the sequence, otherwise am = am−1 + m.
The first few numbers in the Recaman's Sequence is 0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9 ...
Given k, your task is to calculate ak.
The first few numbers in the Recaman's Sequence is 0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9 ...
Given k, your task is to calculate ak.
Input
The input consists of several test cases. Each line of the input contains an integer k where 0 <= k <= 500000.
The last line contains an integer −1, which should not be processed.
The last line contains an integer −1, which should not be processed.
Output
For each k given in the input, print one line containing ak to the output.
Sample Input
7 10000 -1
Sample Output
20 18658
Java AC 代码
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; } } }