Item selectR (link currentTree, int k) {
if (currentTree == emptyTree) {
return NULLitem;
}
if (currentTree->left->size == k) {
return (currentTree->item);
}
if (currentTree->left->size > k) {
return (selectR (currentTree->left, k));
}
return (selectR (currentTree->right, k - 1 - currentTree->left->size));
}
// Treat tree as flattened into an ordered array
//k = rank needed to be found
Item STselect(int k)
{
if (k<0 || k>=sizeOfTree)//if key is negitave or if the key is bigger than the Heads Subtree size report error
{
return NULLitem; //return null since there is no item that has that rank
}
return selectR(head, k);
}
//h=node being investigated, k= key needing to be found
Item selectR(link h, int k)
// See Sedgewick - implements "zero-based indexing".
// Returns the kth smallest key where k=0 returns the smallest
// key. Thus, this is like flattening the tree inorder into an array
// and applying k as a subscript.
{
int t = h->rank;
if (h == z)
{
printf("Impossible situation in selectR\n");
STprintTree();
exit(0);
}
if (t > k){
return selectR(h->l, k);
}
if (t < k){
return selectR(h->r, k-t-1);
}
return h->item;
}
Item STselect(link head, int r) {
return selectR(head, r);
}
Item selectR(link h, int r) {
int t = hl->N;
if (t > r) return selectR(hl, r);
if (t < r) return selectR(hr, r-t-1);
return *(h->item);
}
Item STselect (int k) {
return (selectR (rootNodeLink, k));
}
