(大数)Computer Transformation hdu1041
Computer Transformation Time Limit: 2000/1000 MS (Java/Others)????Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 8688????Accepted Submission(s): 3282 ? ? Problem Description A sequence consisting of one digit,the number 1 is initially written into a computer. At each successive time step,the computer simultaneously tranforms each digit 0 into the sequence 1 0 and each digit 1 into the sequence 0 1. So,after the first time step,the sequence 0 1 is obtained; after the second,the sequence 1 0 0 1,after the third,the sequence 0 1 1 0 1 0 0 1 and so on. ? How many pairs of consequitive zeroes will appear in the sequence after n steps? ? Input Every input line contains one natural number n (0 < n ≤1000). ? Output For each input n print the number of consecutive zeroes pairs that will appear in the sequence after n steps. ? Sample Input 2 3 ? Sample Output 1 1 ? ? ? 用java,递推 递推:0->10 ?; ? ? ? ? ?1->01; ? ? ? ? ?00->1010; ? ? ? ? ?10->0110; ? ? ? ? ? 01->1001; ? ? ? ? ? 11->0101; 假设a[i]表示第i 步时候的00的个数,由上面的可以看到,00是由01 得到的,所以只要知道a[i-1]的01的个数就能够知道a[i]的00的个数了,那a[i-1]怎么求呢,同样看推导,01由1和00 得到,而第i步1的个数是2^(i-1),所以a[i]=2^(i-3)+a[i-2];(最后计算的是第i-2步情况)。 ? import java.math.BigDecimal; import java.math.BigInteger; import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner in = new Scanner(System.in); BigInteger a[]=new BigInteger[1001]; while(in.hasNextInt()) { int n=in.nextInt(); a[1]=BigInteger.valueOf(0); a[2]=BigInteger.valueOf(1); a[3]=BigInteger.valueOf(1); for(int i=4;i<=n;i++) { a[i]=BigInteger.valueOf(0); //先进行初始化。 int m=i-3; //在大数的pow(m,n)中,n是int类型的,m是BigInteger类型的。 BigInteger q= new BigInteger("2"); a[i]=a[i].add(q.pow(m)); a[i]=a[i].add(a[i-2]); } System.out.println(a[n]); } } } (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |