Aggiorna elemento nell'elenco collegato circolare in C
Implementazione
L'implementazione di questo algoritmo è fornita di seguito:
#include <stdio.h>
#include <stdlib.h>
struct node {
int data;
struct node *next;
};
struct node *head = NULL;
struct node *current = NULL;
//insert link at the first location
void insert(int data) {
// Allocate memory for new node;
struct node *link = (struct node*) malloc(sizeof(struct node));
link->data = data;
link->next = NULL;
// If head is empty, create new list
if(head==NULL) {
head = link;
head->next = link;
return;
}
current = head;
// move to the end of the list
while(current->next != head)
current = current->next;
// Insert link at the end of the list
current->next = link;
// Link the last node back to head
link->next = head;
}
void update_data(int old, int new) {
int pos = 0;
if(head==NULL) {
printf("Linked List not initialized");
return;
}
current = head;
while(current->next!=head) {
if(current->data == old) {
current->data = new;
printf("\n%d found at position %d, replaced with %d\n", old, pos, new);
return;
}
current = current->next;
pos++;
}
if(current->data == old) {
current->data = new;
printf("\n%d found at position %d, replaced with %d\n", old, pos, new);
return;
}
printf("%d does not exist in the list\n", old);
}
//display the list
void printList() {
struct node *ptr = head;
printf("\n[head] =>");
//start from the beginning
while(ptr->next != head) {
printf(" %d =>",ptr->data);
ptr = ptr->next;
}
printf(" %d =>",ptr->data);
printf(" [head]\n");
}
int main() {
insert(10);
insert(20);
insert(30);
insert(1);
insert(40);
insert(56);
printList();
update_data(56,11);
printList();
return 0;
}
Produzione
Il risultato del programma dovrebbe essere:
[head] => 10 => 20 => 30 => 1 => 40 => 56 => [head]
56 found at position 5, replaced with 11
[head] => 10 => 20 => 30 => 1 => 40 => 11 => [head]