linked-list - Finding a node Deleting a node
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The document provides an overview of basic operations on linked lists, including finding, deleting, and displaying nodes. It then discusses memory management, including destroying the list and variations like circular and doubly linked lists. Finally, it contrasts linked lists with arrays, highlighting their dynamic nature and efficiency in insertions and deletions.
linked-list - Finding a node Deleting a node
- 1. Linked Lists / Slide 1 Finding a node int FindNode(double x) Search for a node with the value equal to x in the list. If such a node is found, return its position. Otherwise, return 0. int List::FindNode(double x) { Node* currNode = head; int currIndex = 1; while (currNode && currNode->data != x) { currNode = currNode->next; currIndex++; } if (currNode) return currIndex; return 0; }
- 2. Linked Lists / Slide 2 Deleting a node int DeleteNode(double x) Delete a node with the value equal to x from the list. If such a node is found, return its position. Otherwise, return 0. Steps Find the desirable node (similar to FindNode) Release the memory occupied by the found node Set the pointer of the predecessor of the found node to the successor of the found node Like InsertNode, there are two special cases Delete first node Delete the node in middle or at the end of the list
- 3. Linked Lists / Slide 3 Deleting a node int List::DeleteNode(double x) { Node* prevNode = NULL; Node* currNode = head; int currIndex = 1; while (currNode && currNode->data != x) { prevNode = currNode; currNode = currNode->next; currIndex++; } if (currNode) { if (prevNode) { prevNode->next = currNode->next; delete currNode; } else { head = currNode->next; delete currNode; } return currIndex; } return 0; } Try to find the node with its value equal to x
- 4. Linked Lists / Slide 4 Deleting a node int List::DeleteNode(double x) { Node* prevNode = NULL; Node* currNode = head; int currIndex = 1; while (currNode && currNode->data != x) { prevNode = currNode; currNode = currNode->next; currIndex++; } if (currNode) { if (prevNode) { prevNode->next = currNode->next; delete currNode; } else { head = currNode->next; delete currNode; } return currIndex; } return 0; } currNode prevNode
- 5. Linked Lists / Slide 5 Deleting a node int List::DeleteNode(double x) { Node* prevNode = NULL; Node* currNode = head; int currIndex = 1; while (currNode && currNode->data != x) { prevNode = currNode; currNode = currNode->next; currIndex++; } if (currNode) { if (prevNode) { prevNode->next = currNode->next; delete currNode; } else { head = currNode->next; delete currNode; } return currIndex; } return 0; } currNode head
- 6. Linked Lists / Slide 6 Printing all the elements void DisplayList(void) Print the data of all the elements Print the number of the nodes in the list void List::DisplayList() { int num = 0; Node* currNode = head; while (currNode != NULL){ cout << currNode->data << endl; currNode = currNode->next; num++; } cout << "Number of nodes in the list: " << num << endl; }
- 7. Linked Lists / Slide 7 Destroying the list ~List(void) Use the destructor to release all the memory used by the list. Step through the list and delete each node one by one. List::~List(void) { Node* currNode = head, *nextNode = NULL; while (currNode != NULL) { nextNode = currNode->next; // destroy the current node delete currNode; currNode = nextNode; } }
- 8. Linked Lists / Slide 8 Using List int main(void) { List list; list.InsertNode(0, 7.0); // successful list.InsertNode(1, 5.0); // successful list.InsertNode(-1, 5.0); // unsuccessful list.InsertNode(0, 6.0); // successful list.InsertNode(8, 4.0); // unsuccessful // print all the elements list.DisplayList(); if(list.FindNode(5.0) > 0) cout << "5.0 found" << endl; else cout << "5.0 not found" << endl; if(list.FindNode(4.5) > 0) cout << "4.5 found" << endl; else cout << "4.5 not found" << endl; list.DeleteNode(7.0); list.DisplayList(); return 0; } 6 7 5 Number of nodes in the list: 3 5.0 found 4.5 not found 6 5 Number of nodes in the list: 2 result
- 9. Linked Lists / Slide 9 Variations of Linked Lists Circular linked lists The last node points to the first node of the list How do we know when we have finished traversing the list? (Tip: check if the pointer of the current node is equal to the head.) A Head B C
- 10. Linked Lists / Slide 10 Variations of Linked Lists Doubly linked lists Each node points to not only successor but the predecessor There are two NULL: at the first and last nodes in the list Advantage: given a node, it is easy to visit its predecessor. Convenient to traverse lists backwards A Head B C
- 11. Linked Lists / Slide 11 Array versus Linked Lists Linked lists are more complex to code and manage than arrays, but they have some distinct advantages. Dynamic: a linked list can easily grow and shrink in size. We don’t need to know how many nodes will be in the list. They are created in memory as needed. In contrast, the size of a C++ array is fixed at compilation time. Easy and fast insertions and deletions To insert or delete an element in an array, we need to copy to temporary variables to make room for new elements or close the gap caused by deleted elements. With a linked list, no need to move other nodes. Only need to reset some pointers.