Find what Level an Element is in Tree - c

Question

So i've got this problem where I'm supposed to find the level of an element in a tree. Nothing seems to work out so im reaching out here for help.
This is what i've got so far. The problem here is that the 4th assert, where the returned level is supposed to be 2, doesnt work and the assert is alerted. I've thought of maybe trying to not do it recursivly, but how could that be done?
int findElementLevel(const BSTree tree, const int element) {
int level = 0;
if (tree == NULL) {
return -1;
}
if (tree->data == element) {
return level;
}
if (element < (tree)->data) {
level++;
findElementLevel(tree->left, element);
return level;
}
if (element > (tree)->data) {
level++;
findElementLevel(tree->right, element);
return level;
}
}
void testNewTree(void) {
BSTree tree = emptyTree();
assert(isEmpty(tree));
int arr[5] = {3,2,5,1,4}, i;
for (i = 0; i < 5; i++)
{
insertSorted(&tree, arr[i]);
}
assert(findElementLevel(tree, 3) == 0);
assert(findElementLevel(tree, 2) == 1);
assert(findElementLevel(tree, 5) == 1);
assert(findElementLevel(tree, 1) == 2);
assert(findElementLevel(tree, 4) == 2);
}

Answer 1

The function always starts from the declaration of the local variable level that is set to 0.
int findElementLevel(const BSTree tree, const int element) {
int level = 0;
This value that is 0 (or 1 due to its increment in a current recursive function call) )is returned in case when the target element is found in any actual level
if (tree->data == element) {
return level;
}
You have to accumulate levels.
A recursive function can be defined for example the following way
int findElementLevel(const BSTree tree, const int element) {
if (tree == NULL) {
return -1;
}
else if ( element < tree->data ) {
int level = findElementLevel(tree->left, element);
return level == -1 ? level : level + 1;
}
else if ( tree->data < element ) {
int level = findElementLevel(tree->right, element);
return level == -1 ? level : level + 1;
}
else {
return 0;
}
}
Pay attention to that the qualifier const for the second parameter does not make great sense because the function deals with a copy of the value of the supplied argument. The function can be declared just like
int findElementLevel(const BSTree tree, int element);

Answer 2

This function is easier and shorter to write iteratively than recursively. The code is just:
int findElementLevel(const BSTree tree, const int element)
{
for (int level = 0; tree; ++level)
{
if (tree->data == element)
return level;
tree = tree->data < element ? tree->left : tree->right;
}
return -1;
}
With explanation, it is:
int findElementLevel(const BSTree tree, const int element)
{
/* Use a loop to process each level. We start counting levels at zero and
increment on each iteration. We continue as long as there is more of
the tree to explore ("tree" evaluates as true, i.e., non-null), or jump
out of the loop with a return if the target element is found.
*/
for (int level = 0; tree; ++level)
{
// If we found the target, return the level it is on.
if (tree->data == element)
return level;
/* Otherwise, descend to the left or the right according to which
side the target element must be on.
*/
tree = tree->data < element ? tree->left : tree->right;
}
/* If we reached the end of the tree without finding the element, return
-1.
*/
return -1;
}