c++ - 冰雹序列 C++ 递归

Question

我在将以下代码从使用循环转换为仅使用递归时遇到了一些麻烦。

//longestHailstoneStartValue also cycles through each of the sequences from 1 
//to 'n' and after it is determined what the largest length is, it finds which 
//number corresponds with the longest length function.
//
//Sample input: '8'
//Sample output: '7'
//'7' is from the sequence starting with 7.

int longestHailstoneStartValue(int n)
{
    int u=1, w=0, z=0;

while(n>=u)
{
    if(w<lengthHailstone(u))
    {
        w=lengthHailstone(u);
        z=u;
    }

    u++;
}

return z;
}

我必须将其转换为递归，并采用任何未使用/存储有新值的额外变量。

Answer 1

你必须取出变量z，因为它实际上没有用，只是存储u的值，这可以增加复制值的内存u 到 z...

此外，请阅读 recursion to know more about what it actually is ...它只是根据自己的定义一次又一次地调用相同的方法...

int longestHailstoneStartValue(int n)
{
    int u = 1, w = 0;
    if(w < lengthHailstone(u))
        w = lengthHailstone(u); // Removed 'z'...
    u++;
    /* '?' is the ternary operator... If n is greater or equal to u then print the
       original value of u (Note the 'u++') or else recursively call the function till
       the condition 'n >= u' is satisfied... */
    return n >= u ? u - 1 : longestHailstoneStartValue(n); /* 'u - 1' since 'u' will
                                                               increment by 1 even when
                                                               the given condition is
                                                               true... */
}