POJ1207 The 3n + 1 problem

时间：2015-02-13 01:27:48 阅读：160 评论：0 收藏：0 [点我收藏+]

标签：

这题不是很难，模拟一下即可，但有一些细节需要注意

输入的数不一定升序，且要按原顺序输出，还有就是读完数据的问题

The 3n + 1 problem

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 53006		Accepted: 16841

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

Sample Output

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

Source

Duke Internet Programming Contest 1990,uva 100

 1 //oimonster
 2 #include<cstdio>
 3 #include<cstdlib>
 4 #include<iostream>
 5 using namespace std;
 6 int count(int i)  
 7 {  
 8     int s=1;  
 9     while(i!=1)  
10     {  
11         if(i%2)  
12             i=3*i+1;  
13         else  
14             i/=2;  
15         s++;  
16     }  
17     return s;  
18 }  
19 int main(){
20     int i,j,n,max,k,t,ii,jj;
21     while(scanf("%d%d",&i,&j)!=EOF){
22         ii=i;
23         jj=j;
24         if(i>j){
25             t=i;
26             i=j;
27             j=t;
28         }
29         max=0;
30         for(n=i;n<=j;n++){
31             k=count(n);
32             if(k>max)max=k;
33         }
34         printf("%d %d %d\n",ii,jj,max);
35     }
36     return 0;
37 }

View Code

POJ1207 The 3n + 1 problem

标签：

原文地址：http://www.cnblogs.com/oimonster/p/4289471.html

踩

(0)

评论一句话评论（0）

分享档案

更多>

2021年07月29日 (22)
2021年07月28日 (40)
2021年07月27日 (32)
2021年07月26日 (79)
2021年07月23日 (29)
2021年07月22日 (30)
2021年07月21日 (42)
2021年07月20日 (16)
2021年07月19日 (90)
2021年07月16日 (35)

周排行