Data Structure: chain storage structure of linear tables and reverse of Single-Chain tables

In order to express the logical relationship between each data element AI and its direct successor element ai + 1, in addition to storing its own information, data AI also needs to store a command to indicate its

Information of the direct successor (that is, the storage location of the direct successor ). These two pieces of information constitute the storage image of the data element AI, known as the node ). N node chains form a linked list,

This is the chain storage structure of a linear table (A1, A2,..., an). Because each node of this linked list contains only one pointer field, it is called a single-chain table.

The storage location of the first node in the linked list is called the head pointer. To facilitate operations on the linked list, such as the special case of deleting the first node

(The first node does not have a precursor, but to remove a node, you must first find its precursor to perform the removal operation.) A node is often attached to the first node of a single-chain table,

It is called a header node, so the header Pointer Points to the header node.

The advantages and disadvantages of a single-chain table and an array are basically the opposite. That is, a single-chain table has a high insertion and deletion efficiency, while searching requires traversal, which is less efficient.

Example program: (adapted from "big talk Data Structure", added chain table inversion, etc)

C ++ code

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# Include <iostream> # Include <stdlib. h> # Include <time. h> Using namespace STD; Typedef int elemtype; Typedef struct Node { Elemtype data; Struct node * next; } Node; Typedef node * nodeptr; Bool initlist (nodeptr * NPP) { * NPP = (nodeptr) malloc (sizeof (node);/* generate a header node and point * NPP to this header node */ If (! (* NPP )) Return false; // allocation failed (* NPP)-> next = NULL;/* the pointer field is empty */ Return true; } Bool listempty (nodeptr np) { If (NP-> next = NULL) Return true; Else Return false; } Bool clearlist (nodeptr * NPP) { Cout <"clear list..." <Endl; Nodeptr P = * NPP; If (! (P-> next )) Return true; While (p-> next)/* not at the end of the table */ { Nodeptr q = p-> next; P-> next = Q-> next; Free (Q ); } Return true; } Int listlength (nodeptr np) { Cout <"list's length :"; Nodeptr P = NP-> next;/* P points to the first node */ Int I = 0; While (P) { P = p-> next; ++ I; } Return I; } /* Operation result: Use PTR to return the value of the POS data element in NP */ Bool getelem (nodeptr NP, int POs, elemtype * PTR) { Cout <"get item from POS" <POS <":"; Nodeptr P = NP-> next; Int I = 1; /* When P is not empty or the counter I is not equal to POS, the loop continues */ While (P & I <POS) { P = p-> next; ++ I; } If (! P) Return false; * PTR = p-> data;/* obtain the data of the POs element */ Return true; } /* Return the order of the 1st data elements in the NP that match the ELEM. */ /* If such a data element does not exist, the returned value is 0 */ Int locateelem (nodeptr NP, elemtype ELEM) { Cout <"item" <ELEM <"'s pos :"; Nodeptr P = NP-> next; Int I = 1; While (P & P-> data! = ELEM) { P = p-> next; ++ I; } If (! P) Return 0; Return I; } /* Operation result: a new data element ELEM is inserted before the POs position in NP. The length of NP is increased by 1 */ Bool listinsert (nodeptr * NPP, int POs, elemtype ELEM) { Cout <"Insert list POS" <POS <"item" <ELEM <Endl; Nodeptr P = * NPP; Int I = 1; While (P & I <POS) { P = p-> next; ++ I; } If (! P) Return false; Nodeptr in = (nodeptr) malloc (sizeof (node )); In-> DATA = ELEM; In-> next = p-> next;/* assign the successor node of P to the successor node of in */ P-> next = In;/* assign the in value to the successor of p */ Return true; } /* Delete the POS data element of NPP and return its value with PTR. The length of NPP is reduced by 1 */ Bool listdelete (nodeptr * NPP, int POs, elemtype * PTR) { Cout <"delete list item in POS" <POS <Endl; Nodeptr P = * NPP; Int I = 1; While (P & I <POS) { P = p-> next; ++ I; } If (! P) Return false; Nodeptr q = p-> next; * PTR = Q-> data; P-> next = Q-> next;/* assign the Q successor to p */ Free (Q ); Return true; } Bool listtraverse (nodeptr np) { Cout <"list's items :"; Nodeptr P = NP-> next; While (P) { Cout <p-> data <''; P = p-> next; } Cout <Endl; Return true; } /* Randomly generate N element values and create a single-chain linear table NPP (Head Insertion Method) with table header nodes )*/ Void createlisthead (nodeptr * NPP, int num) { Cout <"create list from head..." <Endl; If (* NPP! = NULL) Free (* NPP ); * NPP = (nodeptr) malloc (sizeof (node )); (* NPP)-> next = NULL;/* create a single-chain table with the leading node first */ Srand (Time (null )); For (INT I = 0; I <num; I ++) { Nodeptr P = (nodeptr) malloc (sizeof (node )); P-> DATA = rand () % 100 + 1; // Random Number P-> next = (* NPP)-> next; (* NPP)-> next = P;/* insert to the header */ } } /* Randomly generate N element values, and create a single-chain linear table NPP (tail Insertion Method) with table header nodes )*/ Void createlisttail (nodeptr * NPP, int num) { Cout <"create list from tail..." <Endl; If (* NPP! = NULL) Free (* NPP ); * NPP = (nodeptr) malloc (sizeof (node )); (* NPP)-> next = NULL; Srand (Time (null )); Nodeptr tail = * NPP;/* tail is the node pointing to the end */ For (INT I = 0; I <num; I ++) { Nodeptr P = (nodeptr) malloc (sizeof (node )); P-> DATA = rand () % 100 + 1; Tail-> next = P;/* point the pointer to the End Node of the table to the new node */ Tail = P;/* define the current new node as the end node of the table */ } Tail-> next = NULL; } /* Reverse a single-chain table */ Nodeptr reverselist (nodeptr head) { Cout <"reverse list..." <Endl; If (null = head-> next | null = head-> next) Return head; Nodeptr P; Nodeptr Q; Nodeptr R; P = head-> next; Q = p-> next; Head-> next = NULL; While (q) { R = Q-> next ;// Q-> next = P; P = Q ;// Q = r ;// } Head-> next = P; Return head; } Int main (void) { Nodeptr NP; // header pointer Initlist (& NP ); For (INT I = 1; I <5; I ++) Listinsert (& NP, I, I ); If (! Listempty (NP )) Cout <listlength (NP) <Endl; Listtraverse (NP ); Cout <locateelem (NP, 3) <Endl; Int get; Getelem (NP, 2, & get ); Cout <get <Endl; Clearlist (& NP ); Cout <listlength (NP) <Endl; Createlisthead (& NP, 10 ); Listtraverse (NP ); Int result; Listdelete (& NP, 5, & result ); Listtraverse (NP ); Clearlist (& NP ); Createlisttail (& NP, 10 ); Listtraverse (NP ); Listtraverse (reverselist (NP )); Clearlist (& NP ); Return 0; }

Output:

Note: The single-chain table reversal method used in the program is to use p and q to work together, so that the two nodes are directed to the reverse, and the remaining linked list is recorded with R. It is a single-chain table reversal condition that does not include the header node. There are minor differences between single-chain table reversal with the header node. Be careful.