HDU 1297 Children’s Queue

Children’s Queue

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 8194    Accepted Submission(s): 2603

Problem Description

There are many students in PHT School. One day, the headmaster whose name is PigHeader wanted all students stand in a line. He prescribed that girl can not be in single. In other words, either no girl in the queue or more than one girl stands side by side. The case n=4 (n is the number of children) is like FFFF, FFFM, MFFF, FFMM, MFFM, MMFF, MMMM Here F stands for a girl and M stands for a boy. The total number of queue satisfied the headmaster’s needs is 7. Can you make a program to find the total number of queue with n children?

 

Input

There are multiple cases in this problem and ended by the EOF. In each case, there is only one integer n means the number of children (1<=n<=1000)

 

Output

For each test case, there is only one integer means the number of queue satisfied the headmaster’s needs.

 

Sample Input

1

2

3

 

Sample Output

1

2

4

 

Author

SmallBeer (CML)

 

Source

杭电ACM集训队训练赛（VIII）

 

Recommend

lcy

 

 

 

 

import java.util.*;
import java.math.*;

public class Main{
    public static void main(String[] args){
        Scanner cin = new Scanner(System.in);
        BigInteger []num = new BigInteger[1010];
        num[1] = BigInteger.valueOf(1);
        num[2] = BigInteger.valueOf(2);
        num[3] = BigInteger.valueOf(4);
        num[4] = BigInteger.valueOf(7);
        for(int i=5; i<1001; i++)
            num[i] = num[i-1].add(num[i-2].add(num[i-4]));
        int n;
        while(cin.hasNext()){
            n = cin.nextInt();
            System.out.println(num[n]);
        }
    }
}