CODEWITHSUNDEEP
crecursionbinary-tree
JimHalpert
JimHalpert

Reputation: 11

Trying to add up the values of every node in a binary tree, recursively

I keep getting an error for invalid operand in return expression, I'm trying to recursively code a function to take every value in two different trees and add them together to create one tree but I keep getting an error, any help would be greatly appreciated!

node_t * addTree(node_t * t1, node_t * t2)
{
  if(t1 != NULL || t2 != NULL)
  {
    t1->data = t1->data + t2->data;
    return addTree(t1=t1->rightchild, t2=t2->rightchild)+addTree(t1=t1->rightchild, t2=t2->leftchild)+addTree(t1=t1->leftchild, t2=t2->rightchild)+addTree(t1=t1->leftchild, t2=t2->leftchild);
  }
  else
    return t1;
}

Upvotes: 0

Views: 36

Answers (1)

David Grayson
David Grayson

Reputation: 87416

Something like this should work. It uses a little trick so we only need a few null checks instead of many.

node_t * addTree(const node_t * t1, const node_t * t2)
{
  if (t1 == NULL && t2 == NULL) { return NULL; }

  const node_t nullNode = {};
  if (t1 == NULL) { t1 = &nullNode; }
  if (t2 == NULL) { t2 = &nullNode; }

  node_t * r = malloc(sizeof(node_t));
  r->data = t1->data + t2->data;
  r->leftchild = addTree(t1->leftchild, t2->leftchild);
  r->rightchild = addTree(t1->rightchild, t2->rightchild);
  return r;
}

Upvotes: 1

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