hdu 1297 Children’s Queue(java+简单dp)

来源：互联网发布：西门子消防主机软件编辑：程序博客网时间：2024/04/27 19:32

Children’s Queue

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 11519 Accepted Submission(s): 3746

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

Sample Output

Author

SmallBeer (CML)

题目分析：
这道题最终结果会超long long ，所以我选择了java
状态定义为dp[i][j][k],i标记当前状态是否合法，j标记最后一位是男还是女，k标记当前位；
之所以定义非法状态，是因为当前位选择女性导致的非法，可能在后一位被纠正为合法
具体转移过程见代码，其实如果java中全部定义为static，和c++基本上在编程上是没区别的

package hdu;import java.util.Scanner;import java.math.BigInteger;public class Main {static BigInteger [][][]dp = new BigInteger[3][3][1007];static void memset ( ){for ( int i = 0 ; i < 3 ; i++ )for ( int j = 0 ; j < 3 ; j++ )for ( int k = 0 ; k < 1007 ; k++ )dp[i][j][k] = BigInteger.ZERO;}static void init ( ){ memset (); dp[1][1][1] = dp[0][2][1] = BigInteger.ONE; for ( int i = 2 ; i <= 1000 ; i++  ) { dp[1][1][i] = dp[1][2][i-1].add(dp[1][1][i-1]); dp[1][2][i] = dp[1][2][i-1].add(dp[0][2][i-1]); dp[0][2][i] = dp[1][1][i-1]; }}public static void  main ( String args[] ){Scanner cin = new Scanner ( System.in );init();while ( cin.hasNext() ){int n = cin.nextInt();System.out.println ( dp[1][1][n].add(dp[1][2][n]) );}}}

0 0