爱尔兰根大学今年ACM大赛内部选拔样题

kurz

The 3n + 1 problem

Background
Problems in Computer Science are often classified as belonging to a certain class of problems (e.g., NP, Unsolvable, Recursive). In this problem you will be analyzing a property of an algorithm whose classification is not known for all possible inputs.

The Problem
Consider the following algorithm:


1. input n

2. print n

3. if n = 1 then STOP

4. if n is odd then n/2

5. else 3n+1

6. GOTO 2


Given the input 22, the following sequence of numbers will be printed 22 11 34 17 52 26 13 40 20 10 5 16 8 4 2 1

It is conjectured that the algorithm above will terminate (when a 1 is printed) for any integral input value. Despite the simplicity of the algorithm, it is unknown whether this conjecture is true. It has been verified, however, for all integers n such that 0 < n < 1,000,000 (and, in fact, for many more numbers than this.)

Given an input n, it is possible to determine the number of numbers printed (including the 1). For a given n this is called the cycle-length of n. In the example above, the cycle length of 22 is 16.

For any two numbers i and j you are to determine the maximum cycle length over all numbers between i and j.


The Input
The input will consist of a series of pairs of integers i and j, one pair of integers per line. All integers will be less than 1,000,000 and greater than 0.

You should process all pairs of integers and for each pair determine the maximum cycle length over all integers between and including i and j.


The Output
For each pair of input integers i and j you should output i, j, and the maximum cycle length for integers between and including i and j. These three numbers should be separated by at least one space with all three numbers on one line and with one line of output for each line of input. The integers i and j must appear in the output in the same order in which they appeared in the input and should be followed by the maximum cycle length (on the same line).


Sample Input

1 10
100 200
201 210
900 1000


Sample Output

1 10 20
100 200 125
201 210 89
900 1000 174

kurz

给定N枚硬币，其中有正面的有反面的，每次只能翻动相邻的3个，要求将硬币翻到所要的状态:全是正面，或全是反面
要求用最少的步骤完成，并打印出步骤
输入方法：1代表正面，0代表反面
比如1000111
对结果的要求 1
就是说硬币的排列是正反反反正正正 要求全部结果为正