chapter2-Linear List.pptVIP

计算机科学与工程系 计算机科学与工程系 Chapter 2 Linear List Conceptions ADT Sequential Implementation Linked List Example: Polynomials 2.1 Conceptions ADT 1）Definition：A list is a finite sequence of data elements from the same data type. Notation 记为 : L a1, a2, …, an） name a1 is the list head，an is the last element n is the length of the list. If n 0, we call the list an empty list. ai-1 is the directly predecessor prior of ai ai+1 is the directly successor next of ai 2.1 Conceptions ADT A list is a data structure where data is represented linearly. For a List not empty There is one and only “head” element There is one and only “last” element Except the list head, every element has one and only one directly predecessor. Except the last element, every element has one and only one directly successor. 2）ADT of Linear List ADT List Objects: D＝ ai | ai ∈ElemSet, i 1,2,...,n, n≥0 Function: R1＝ ai-1 ,ai | ai-1 ,ai∈D, i 2,...,n InitList L DestroyList L ListEmpty L ListLength L GetElem L, i, e … … ADT List 2.2 Sequential Implementation of List 1 Array-based List 3）Operations on Array-based List ② Retrieve the i’th element ③ Insert a new element at the position i ④ Delete the element at position i ⑤ Find the first occurrence of X ⑤ Find the first occurrence of X Summary of array-based list Array implementation of list adjacent elements logically are adjacent too in memory Random Access disadvantage Element movements during insertion and deletion Waste considerable space in storing the list of varying size possible solution linked list linked lists are dynamically allocated 2.3 Linked List Linked list Adjacent elements logically are not necessarily adjacent in memory. Instead, data is stored at random locations and the current data location provides the information regarding the location of the next data. Elements connected by pointer links. Using pointers to point to the next element. Use a linked list instead of an array when You have an unpredictab