c program for double link list
#include <stdio.h> #include <string.h> #include <stdlib.h> #include <stdbool.h> struct node { int data; int key; struct node *next; struct node *prev; }; //this link always point to first Link struct node *head = NULL; //this link always point to last Link struct node *last = NULL; struct node *current = NULL; //is list empty bool isEmpty(){ return head == NULL; } int length(){ int length = 0; struct node *current; for(current = head; current != NULL; current = current->next){ length++; } return length; } //display the list in from first to last void displayForward(){ //start from the beginning struct node *ptr = head; //navigate till the end of the list printf("\n[ "); while(ptr != NULL){ printf("(%d,%d) ",ptr->key,ptr->data); ptr = ptr->next; } printf(" ]"); } //display the list from last to first void displayBackward(){ //start from the last struct node *ptr = last; //navigate till the start of the list printf(...