_node* search (_node* head, _key key) { _node* node; for (node=head; node != NULL;;) { if (key == node->key) return node; else if (key < node.>key) node = node->left; else node = node->right; } return node; }
Given a list and a node to delete, use the following algorithm: // Are we deleting the head node? if (node == list.head) { // Yes -- assign its next node as the new head list.head = node.next } else // The node is not the head node { // Point to the head node prev = list.head // Traverse the list to locate the node that comes immediately before the one we want to delete while (prev.next != node) { prev = prev.next; } end while // Assign the node's next node to the previous node's next node prev.next = node.next; } end if // Before deleting the node, reset its next node node.next = null; // Now delete the node. delete node;
No. A leaf node is a node that has no child nodes. A null node is a node pointer that points to the null address (address zero). Since a leaf node has no children, its child nodes are null nodes.
For a singly-linked list, only one pointer must be changed. If the node about to be deleted (let's call it node for the sake of argument) is the head of the list, then the head node pointer must be changed to node->next. Otherwise, the node that comes before the deleted node must change its next pointer to node->next. Note that given a singly-linked node has no knowledge of its previous node, we must traverse the list from the head in order to locate that particular node, unless the node is the head of the list: void remove (List* list, Node* node) { if (!list !node) return; // sanity check!if (list->head == node) {list->head = node->next;} else {Node* prev = list->head;while (prev->next != node) prev = prev->next; // locate the node's previous nodeprev->next = node->next;}} Note that the remove function only removes the node from the list, it does not delete it. This allows us to restore the node to its original position, because the node itself was never modified (and thus still refers to its next node in the list). So long as we restore all removed nodes in the reverse order they were removed, we can easily restore the list. In order to delete a node completely, we simply remove it and then free it:void delete (List* list, Node* node) {if (!list !node) return; // sanity check!remove (list, node);free (node);} For a doubly-linked list, either two or four pointers must be changed. If the node about to be deleted is the head node, then the head node pointer must be changed to n->next and n->next->prev must be changed to NULL, otherwise, n->prev->next becomes n->next. In addition, if the node about to be deleted is the tail node, then the tail node pointer must be changed to n->prev and n->prev->next must be changed to NULL, otherwise, n->next->prev becomes n->prev. Deletion from a doubly-linked list is generally quicker than deletion from a singly linked list because a node in a doubly-linked list knows both its previous node and its next node, so there's no need to traverse the list to locate the previous node to the one being deleted. void remove (List* list, Node* node) {if (!list !node) return; // sanity check!if (list->head == node) {list->head = node->next;node->next->prev = NULL;} else {node->prev->next = node->next; }if (list->tail == node) {list->tail = node->prev;node->prev->next = NULL;} else {node->next->prev = node->prev; }} Again, to physically delete the node we simply remove and then free the node:void delete (List* list, Node* node) {if (!list !node) return; // sanity check!remove (list, node); free (node); }
In this case recursion is not necessary, an iterative process is more efficient. Start by pointing at the head node. While this node has a next node, detach its next node and insert that node at the head. Repeat until the original head node has no next node. At that point the head has become the tail and all the nodes are completely reversed. The following example shows how this can be implemented, where the list object contains a head node (which may be NULL), and each node has a next node. The tail node's next node is always NULL. void reverse(list& lst) { if( node* p=lst.head ) { while(p->next) { node* n=p.next; // point to the next node p.next=n.next; // detach the next node n.next=lst.head; // insert the detached node at the head lst.head=n; // set the new head node } } }
The sinoatrial node triggers an impulse
SA node
SA node sends an impulse for the atria to contract. AV node is then activated which contracts the ventricles.
In the Sinoatrial Node
It is supposed to be the sinus node and the conducting tissue. It includes the AV node and bundle of HIS. The sinus node generate the impulse in the heart for contraction. The AV node and bundle of HIS transmits the impulse to the ventricles.
This is called saltatory conduction.
sinoatrial (SA) node, atrioventricular (AV) node, atrioventricular (AV) bundle, right and left bundle branches, Perkinje fibers
P-R interval
The heart beats regularly because it has it's own pacemaker. The pacemaker is a small region of muscle called the sinoatrial, or SA, node. It is in the upper back wall of the right atrium. The node triggers an impulse that causes both atrium to contract. Very quickly, the impulse reaches the atrioventricular, or AV, node at the bottom of the right atrium. Immediately, the atrioventricular node triggers an impulse that causes both ventricles to contract.
When the Sino-atrial node fails momentarily to initiate an impulse, sinus arrest occurs. When the sino-atrial node fails momentarily to initiate an impulse, sinus arrest occurs.
Coz they iz ard
Saltatory Conduction