Lecture%2010%20-%20%20Linked%20List%20Operations

Lecture%2010%20-%20%20Linked%20List%20Operations - Lecture...

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Copyright @ 2009 Ananda Gunawardena Lecture 10 Linked List Operations In this lecture Concept of a linked list revisited Types of Linked Lists Designing a node of a Linked List Operations on Linked Lists o Appending a node to a Linked List o Prepending a node to a linked list o Inserting a node in order to a linked list o Deleting a node from a linked list o Reversing a Linked List Doubly Linked Lists Further Readings Exercises Concept of a linked list revisited Static arrays are structures whose size is fixed at compile time and therefore cannot be extended or reduced to fit the data set. A dynamic array can be extended by doubling the size but there is overhead associated with the operation of copying old data and freeing the memory associated with the old data structure. One potential problem of using arrays for storing data is that arrays require a contiguous block of memory which may not be available, if the requested contiguous block is too large. However the advantages of using arrays are that each element in the array can be accessed very efficiently using an index. However, for applications that can be better managed without using contiguous memory we define a concept called “linked lists”. A linked list is a collection of objects linked together by references from one object to another object. By convention these objects are named as nodes . So the basic linked list is collection of nodes where each node contains one or more data fields AND a reference to the next node. The last node points to a NULL reference to indicate the end of the list. image source: Weiss Data Structures
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Copyright @ 2009 Ananda Gunawardena The entry point into a linked list is always the first or head of the list. It should be noted that head is NOT a separate node, but a reference to the first Node in the list. If the list is empty, then the head has the value NULL. Unlike Arrays, nodes cannot be accessed by an index since memory allocated for each individual node may not be contiguous. We must begin from the head of the list and traverse the list sequentially to access the nodes in the list. Insertions of new nodes and deletion of existing nodes are fairly easy to handle and will be discussed in the next lesson. Recall that array insertions or deletions may require adjustment of the array (overhead), but insertions and deletions in linked lists can be performed very efficiently. Types of Linked Lists Linked lists are widely used in many applications because of the flexibility it provides. Unlike arrays that are dynamically assigned, linked lists do not require memory from a contiguous block. This makes it very appealing to store data in a linked list, when the data set is large or device (eg: PDA) has limited memory. One of the disadvantages of linked lists is that they are not random accessed like arrays. To find information in a linked list one must start from the head of the list and traverse the list sequentially until it finds (or not find) the node. Another advantage of linked lists over arrays is that when a
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Lecture%2010%20-%20%20Linked%20List%20Operations - Lecture...

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