Linear tables-04. Chain Storage structure (bidirectional loop linked list)

The following is a linear table implemented with a bidirectional cyclic link list

#include <stdio.h> #include <stdlib.h> #include <time.h> #define OK 1#define ERROR 0#define TRUE Define FALSE 0typedef int Elemtype;//elemtype Here is assumed to be int, can be changed as needed typedef int STATUS;//STATUS is the type of function, whose value is the function result status code, such as OK and other typedef struct DULNODE//linear table of the bidirectional list storage structure {elemtype data;struct dulnode *prior;//Direct precursor pointer struct Dulnode *next;//direct successor} dulnode;/* Initializes a bidirectional loop linked list */status initlist (Dulnode **l) {*l= (Dulnode *) malloc (sizeof (Dulnode)); *l)) return ERROR, (*l)->next= (*l)->prior=*l;return OK;} /* Initial condition: Chain linear table L already exists *//** operation result: Returns the number of data elements in L */int listlength (Dulnode *l) {int I=0;dulnode *p=l->next;while (p!=l) {p=p- >next;i++;} return i;} /* Initial conditions: bidirectional cyclic link list L already exists, 1≤i≤listlength (l) +1*//* operation result: Insert new data element in L position e,l length plus 1*/status listinsert (dulnode *l,int I, Elemtype e) {int J;dulnode *p,*s;//p points to the previous node to be inserted, S is the new node if (i<1)//The insertion position is unreasonable return error;p=l;j=1;while (j<i)/* Find the first node of the I node */{p=p->next;j++;if (p==l)//not found return ERROR;} s= (Dulnode *) malloc (sizeof (Dulnode)); S->data=e;s->prior=p;s->next=p->next;p->next->prior=s;p->next=s;return OK;} /* Initial conditions: bidirectional cyclic link list L already exists//* operation result: Each data element of output L */status listtraverse (Dulnode *l) {dulnode *p=l->next;while (p!=l) {printf ("%d ", P->data);p =p->next;} printf ("\ n"); return OK;} /* Initial conditions: Two-way circular linked list L already exists. /* Operation Result: Returns True if L is a blank table, otherwise false */status Listempty (Dulnode *l) {if (l->next==l && l->prior==l) return True    ; else return FALSE;} /* Initial conditions: Two-way circular linked list L already exists. *//* operation Result: Resets L to empty table. */status clearlist (Dulnode *l) {Dulnode *p;//p points to the first node P=l->next;while (p!=l) {p=p->next;free (p->prior);} The two pointer fields of the l->next=l->prior=l;//head node point to their own return OK; /* Initial conditions: bidirectional cyclic link list L already exists, 1≤i≤listlength (l) *//* operation result: Returns the value of the I data element in L with E */status getelem (dulnode *l,int i,elemtype *e) {Dulnode * P;int j;if (i<1)//value position unreasonable return error;p=l->next;//p point to the first node J=1;while (p!=l&&j<i) {p=p->next;j++;} if (p==l)//First Data element does not exist return Error;*e=p->data;return OK;} /* Initial condition: bidirectional cyclic link list L already exists *//* operation result: Returns the bit order of the 1th data element in L that satisfies the relationship with E.    *//* if such a data element does not exist, the return value is 0*/status Locateelem (Dulnode *l,elemtype e) {int i=0; Dulnode *p=l->nexT        while (p!=l) {i++;        if (p->data==e)/* Find such data element */return I;    p=p->next; } return 0;} /* Initial conditions: Two-way cyclic link list L already exists, 1≤i≤listlength (l) *//* operation Result: Delete the I data element of L, and return its value with E, */status listdelete (dulnode *l,int i,elemtype *e) { Dulnode *p;//p points to the I node int j;p=l->next;j=1;if (I&LT;1)//delete position unreasonable return Error;while (p!=l&&j<i) {p=p-> next;j++;} if (p==l)//First Data element does not exist return Error;*e=p->data;p->prior->next=p->next;p->next->prior=p->prior ; free (p); return OK;} /* Initial conditions: bidirectional cyclic link list L already exists//* operation result: Returns the value of the first Data element value of Cur_e in L pre_e*/status Priorelem (dulnode *l,elemtype cur_e,elemtype *pre_ e) {Dulnode *p;p=l->next;while (p!=l) {if (p->data==cur_e)//Find data element cur_e Node {if (p->prior==l)// If the node is the first node return Error;*pre_e=p->prior->data;return OK;} P=p->next;} return ERROR;} /* Initial conditions: bidirectional cyclic link list L already exists//* operation result: Returns the value of the cur_e of the first Data element value in L pre_e*/status Nextelem (dulnode *l,elemtype cur_e,elemtype *next_ e) {Dulnode *p;p=l->next;while (p!=l) {if (p->data==cur_e)//Find data element cur_e node {if(p->next==l)//If the node is the last node return Error;*next_e=p->next->data;return OK;} P=p->next;} return ERROR;} int main () {Dulnode *l;//head pointer int i,j,k; Elemtype e; Status s;initlist (&l);p rintf ("After initializing L: Listlength (l) =%d\n", Listlength (L)); for (j=1;j<=5;j++) I=listinsert (    L,1,J);p rintf ("After the table head in L is inserted in the following: L.data ="); Listtraverse (L);    printf ("Listlength (l) =%d \ n", Listlength (l));    I=listempty (L);    printf ("L" is empty: i =%d (1: Yes 0: NO) \ n ", i); I=clearlist (L);    printf ("Empty L: listlength (l) =%d\n", Listlength (l));    I=listempty (L);    printf ("L" is empty: i =%d (1: Yes 0: NO) \ n ", I); for (j=1;j<=10;j++) Listinsert (L,J,J);    printf ("After the footer of L is inserted in 1~10: L.data ="); Listtraverse (L); printf ("listlength (l) =%d \ n", Listlength (l));    Listinsert (l,1,0);    printf ("The table header in L is inserted after 0: L.data =");     Listtraverse (L); printf ("listlength (l) =%d \ n", Listlength (l));    Getelem (l,5,&e);        printf ("The value of the 5th element is:%d\n", e); for (j=3;j<=4;j++) {K=locateelem (l,j); if (k) printf ("The bit order of elements with value%d is%d\n"), j,k);    else printf ("no element with a value of%d \ n", j); }k=listlength (L); K is the table length for (j=k+1;j>=k;j--) {i=listdelete (l,j,&e);//Delete the first J data if (I==error) printf ("Delete        %d data failed \ n ", j);    else printf ("Delete element%d value is:%d\n", j,e);    } printf ("Output the elements of L sequentially:"); Listtraverse (L);    j=5; Listdelete (l,j,&e);    Delete the 5th Data printf ("Delete element%d value is:%d\n", j,e);    printf ("Output the elements of L sequentially:"); Listtraverse (L);    I=clearlist (L);    printf ("\ n empty L: listlength (l) =%d\n", Listlength (L)); for (j=1;j<=10;j++) Listinsert (L,J,J);    printf ("After the footer of L is inserted in 1~10: L.data ="); Listtraverse (L); printf ("listlength (l) =%d \ n", Listlength (L));p rintf ("\ n"); for (j=1;j<=10;j++) {S=priorelem (l,j,&e); if (s==error) printf ("element%d has no precursor \ n", j); elseprintf ("The precursor of element%d is%d\n", j,e);} printf ("\ nthe subsequent judgment \ n"); for (j=1;j<=10;j++) {S=nextelem (l,j,&e); if (s==error) printf ("element%d has no successor \ n", j); Elseprintf ( "The successor of element%d is%d\n", j,e);}}

Linear tables-04. Chain Storage structure (bidirectional loop linked list)