The 3n + 1 problem
| Time Limit: 1000MS | Memory Limit: 10000K | |
| Total Submissions: 50513 | Accepted: 15986 |
Description
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.
Consider the
following algorithm:
1. input n
2. print n
3. if n = 1 then STOP
4. if n is odd then n <-- 3n+1
5. else n <-- n/2
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 before the 1 is printed. 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.
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
10,000 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.
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
Source
Duke Internet Programming Contest 1990,uva
100
简单直述式模拟，水题，主要注意输出时n,m必须按照输入时候的顺序输出，我们在程序操作时调换了大小了