CODEWITHSUNDEEP
c
badc0re
badc0re

Reputation: 3523

3n+1 weird stuff happening

While simulating the Colatz Conjecture problem i have made recursion when i want to print the count number in the recursion i get the result i need but when the function return the result it gives me weird numbers, why is that?

#include <stdio.h>
#include <stdlib.h>

int divide(int n,int count){

    if(n<=1){printf("%d ",count);return count;} 

    if(n%2==1){divide(n=3*n+1, ++count);}
    else{divide(n/=2, ++count);}
}
int main(void) {  
    printf("%d ",divide(10,1)); 
    return 0;
}

Upvotes: 1

Views: 128

Answers (3)

Roee Gavirel
Roee Gavirel

Reputation: 19453

A. you need to return the returned value from the recursion calls.
B. why do you assign a value to n in the calls to divide? 

#include <stdio.h>
#include <stdlib.h>

int divide(int n,int count){

    if(n<=1){printf("%d ",count);return count;} 

    if(n%2==1)
    {
        return divide(3*n+1, ++count);
    }
    else
    {
        return divide(n/2, ++count);
    }
}
int main(void) {  
    printf("%d ",divide(10,1)); 
    return 0;
}

Upvotes: 3

Kerrek SB
Kerrek SB

Reputation: 477378

You need to return the results of the recursive calls:

if (n % 2) { return divide(3 * n + 1, count + 1); }
//           %%%%%%
else       { return divide(n / 2, count + 1); }

Note that there's no point in assigning to the local variables, so I've changed that to simple computations.

Upvotes: 8

md5
md5

Reputation: 23717

You don't have any default return. So the return value is undefined.

Upvotes: 9

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