我似乎无法使我的largestLength递归函数工作。

Question

无法使最大长度函数正确工作。

Everything else works perfectly. The function has to be recursive.
Assignment: 1a
Author:     Cory Church
File:       hailstone.cpp
Tab stops:  3

问题： Hailstone程序读取一个int，然后计算并打印该数字的冰雹序列。它还打印序列的长度，序列中的最大数，它们是多少个奇数，然后是从一个到读取的数的最长序列。

示例：

与方案的互动：

从7开始冰雹序列是7 22 11 34 17 52 52 26 13 40 10 16 8 4 2 1序列的长度为17.6。序列中最大的数目是52。最长的冰雹序列以7开头，长度为17。

#include <cstdio>
using namespace std;
#include <algorithm>

// ****************************************************************************
/* next(n) returns the value of the next value in the hailstone
   sequence when the current value is n.

   Example: next(7) = 22 and next(22) = 11.
*/ 

   int next(int n)
   {
      int i = n;
      if (i % 2 == 0)
      {
         i = i/2;
      }
      else 
      { 
         i = 3 * i + 1;
      }
      return (i);
   }
// ****************************************************************************

/* printHailstoneSequence(n) writes out all of the values of the hailstone 
   sequence starting with n.

   Example: printHailstoneSequence(7);
            7 22 11 34 17 52 26 13 40 20 10 5 16 8 4 2 1
*/ 

   void printHailstoneSequence(int n)
   {
      int hail = n;  
      if (hail == 1)
      {
         printf("%i ", hail);
      }
      else
      {
         printf("%i ", hail);
         printHailstoneSequence(next(hail));
      }
   }
// ****************************************************************************

// length(n) returns the length of the Hailstone sequence of n.

// Example: length(7) = 17



   int length(int n)
   {
      int hail = n;  
      if(hail == 1)
      {
         return 1;
      }
      else
      {
         return 1+length(next(hail));
      }

   }
// ****************************************************************************

/* largest(n) determines the largest number of the Hailstone sequence 
   starting with n.

   Example: largest(7)= 52
*/ 

   int largest(int n)
   {
      int hail = n;  
      if (hail == 1)
      {
         return 1;
      }
      else
      {
         return max(largest(next(hail)), hail);
      }

   }
// ****************************************************************************

/* odd(n) determines the number of odd numbers in the Hailstone sequence
   starting with n.

   Example: odd(7)= 6
*/ 

   int odd(int n)
   {
      if (n==1)
      {
         return 1;
      }
      else if (n%2 == 0)
      {
         return odd(next(n));
      }
      else
      {
         return 1+ odd(next(n));
      }

   }
// ****************************************************************************

/* largestLength(n) determines the longest length of any Hailstone sequence
   from 1 to n.

   Example: largestLength(7)= 17
*/ 

   int largestLength(int n)
   { 
      if (n == 1)
      {
         return 1;
      }
      else
      {  
         return max(length(n),largestLength(length(n-1)));
      }

   }
// ****************************************************************************


int main(int argc, char** argv)
{
   int n;
   printf("What number should I start with? ");
   scanf("%i", &n);

   printf("The hailstone sequence starting at %i is\n", n);
   printHailstoneSequence(n);
   printf("\n");
   printf("The length of the sequence is %i. \n", length(n));
   printf("%i of the numbers are odd. \n", odd(n));
   printf("The largest number in the seguence is %i. \n", largest(n));
   printf("The longest hailstone sequence starting with a number up to %i has the length %i \n", n, largestLength(n));

   return 0;
}

Answer 1

在largestLength函数中有一个错误：

return max(length(n),largestLength(length(n-1)));

应该是

return max(length(n),largestLength(n-1));