C语言基础-3N+1问题！！

落日映苍穹つ 2022-03-10 12:54 273阅读 0赞

**输入将由一系列整数i和j组成，每行一对整数。  
处理所有整数对，并为每对确定i和j之间的所有整数的最大周期长度  
对于每对输入整数i和j，应输出i、j以及i和j之间的整数的最大周期长度。这三个数字 应至少用一个空格分隔，其中所有三个数字在一行上，每行输入输出一行。整数i和j必 须以它们在输入中出现的相同顺序出现在输出中，并应后跟最大周期长度（在同一行）**

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  
**代码如下：**

# include <stdio.h>
    int xh(int n){
    	int sum=1;
    	while(n!=1){
    	if(n%2==0){
    		n=n/2;
    	}
    	else{
    		n=n*3+1;
    	}
    	sum++;
    	}
    	return sum;
    }
    int main(){
    	int i,j,k,m,n,m1,n1;
    	int s;
    	while(scanf("%d%d", &m, &n)!=EOF){
                    int c=0;
    		m1=m;
    		n1=n;
    	if(m>n){
    		int t;
    		t=m;
    		m=n;
    		n=t;
    }
     
       for(k=m;k<=n;k++){
        if((s=xh(k))>c){
        	c=s;
    	}
       }
       printf("%d %d %d\n", m1, n1, c);
    }
    	return 0;
    }