A grammar question about c++ - 


binarytree* sortedlisttobst(listnode *& list, int start, int end) {   if (start > end) return null;   // same (start+end)/2, avoids overflow   int mid = start + (end - start) / 2;   binarytree *leftchild = sortedlisttobst(list, start, mid-1);   binarytree *parent = new binarytree(list->data);   parent->left = leftchild;   list = list->next;   parent->right = sortedlisttobst(list, mid+1, end);   return parent; }  binarytree* sortedlisttobst(listnode *head, int n) {   return sortedlisttobst(head, 0, n-1); }

this function transferring sorted list bst.. don't understand in 1st line. why "listnode *&"... if "listnode*" why wrong? thank explanation.

thanks. 1 more question.. if "listnode &list" must wrong, why need "*" also,.. amateur of c++ forgive me stupid question

this reference pointer. changes make listnode (making point @ else) affect variable passed function.

if remove this, recursive calls, e.g. binarytree *leftchild = sortedlisttobst(list, start, mid-1);, modify copy of list instead of actual list, , code behave differently.


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