Geekers Point

C program for inserting elements in circular Linkedlist

#include <stdio.h>
#include <stdlib.h>

//structure of node 
struct node{
int data;
struct node *link;
};

 //prototype declaration
void insert(struct node **,struct node **,int );
void display(struct node *);

int main(){
struct node *front;
struct node *rear;
front=rear=NULL;
insert(&front,&rear,10);
insert(&front,&rear,32);
insert(&front,&rear,30);
insert(&front,&rear,50);
insert(&front,&rear,42);
insert(&front,&rear,60);

display(front);
return 0;
}

//inserting elements in the circular linked list 
void insert(struct node **f,struct node **r,int num){
struct node *temp;

//allocating memory for the temp pointer
temp=(struct node *)malloc(sizeof(struct node));
temp->data=num;

if((*f)==NULL){
*f=temp;
}
else
(*r)->link=temp;

//last element that is rear sholud point to the front element that is front ,point it's link to front *r=temp;
(*r)->link=*f;

}

//display the elements from front
void display(struct node *f){
struct node *p,*q;
p=NULL;
//q pointer points to the first element that is front
q=f;
while(q!=p){
printf("%d ",q->data);
q=q->link;

p=f;
}
}

 C program to sort  elements in Linkedlist

//we are going to sort the elements in the linkedlist using selection sort having efficiency O(n).
#include <stdio.h>
#include <stdlib.h>

struct node{
    struct node *link;
    int data;
    };
  
    void insert(struct node **,int);
    void display(struct node *);
    int count(struct node *);
    void sort(struct node *);
   
    int main(){
        struct node *s;
        s=NULL;
        insert(&s,70);
        insert(&s,20);
        insert(&s,40);
        insert(&s,50);

        display(s);
        sort(s);
        display(s);
      
        count(s);
        return 0;
    }
  
    void insert(struct node **s,int num){
        struct node *temp;
        temp=(struct node*)malloc(sizeof(struct node));
        temp->data=num;
        temp->link=*s;
        *s=temp;
    }
    void display(struct node *s){
   
        while(s!=NULL){
            printf("%d \n",s->data);
            s=s->link;
        }
        printf("\n");
    }

int count(struct node *s){
        int i;
        i=0;
        while(s!=NULL){
          
            s=s->link;
            i++;
        }
        printf("%d",i);
    }
//Selection sort 
void sort(struct node *s){
   struct node *p,*q;
   int temp;
   p=s;
   while(p!=NULL){
       q=p->link;
       while(q!=NULL){
           if(p->data < q->data){
               temp=p->data;
               p->data=q->data;
               q->data=temp;
               
           }
           q=q->link;
           
       }p=p->link;
   }
   }
 Executing the program....
$demo

50 
40 
20 
70 
After sort
70 
50 
40 
20 

4

  

#include <stdio.h>
#include <stdlib.h>

struct node{
    int data;
    struct node *left;
    struct node *right;
    
};

void insert(struct node **,int);
void postorder(struct node *);
void delete(struct node **,int,struct node **);

int main(){
    struct node *s;
    s=NULL;
    insert(&s,11);
    insert(&s,13);
    postorder(s);
    printf("\n");
    delete(&s,11,NULL);
    printf("\n");
    postorder(s);
    return 0;
}

void insert(struct node **s,int num){
    if((*s)==0){
        (*s)=(struct node *)malloc(sizeof(struct node));
        (*s)->left=0;
        (*s)->data=num;
        
        (*s)->right=0;
    }
  
    else if(num<((*s)->data)){
        insert(&((*s)->left),num);
    }
  
    else if(num>((*s)->data)){
        insert(&((*s)->right),num);
    }

      
}
 void postorder(struct node *s){
     
        
        if(s!=NULL){
            
            postorder(s->left);
            postorder(s->right);
            printf("%d ",s->data);
        }else
        return;
     }
void delete(struct node **s,int num,struct node **f){
    struct node *temp;
    if((*s)->data==num){
        if(((*s)->left==NULL) && ((*s)->right==NULL)){
        temp=&(*s);
        free(*s);
        (*s)=NULL;
        }
//only delete if right node present and left should be null
        else if(((*s)->left==NULL) && ((*s)->right!=NULL)){
            free(*s);
            (*s)=(*s)->right;
        }

else if(((*s)->left!=NULL) && ((*s)->right==NULL)){
            free(*s);
            (*s)=(*s)->left;
        }
    }    
        
    }
output
$demo

13 11 

13 

// C implementation of above program. #include <stdio.h> #include <stdlib.h> // A nexted list node struct node {     int data;     struct node *next; };  /* Function to insert a node at the beginning */ void push(struct node ** head_ref, int new_data) {     struct node* new_node = (struct node*) malloc(sizeof(struct node));     new_node->data  = new_data;     new_node->next = (*head_ref);     (*head_ref)  = new_node; } /* Utility function to print a singly linked list */ void printList(struct node *head) {     struct node *temp = head;     while (temp != NULL)     {         printf("%d ", temp->data);         temp = temp->next;     }     printf("\n"); } // Main function that inserts nodes of linked list q into p at alternate // positions. Since head of first list never changes and head of second list // may change, we need single pointer for first list and double pointer for // second list. void merge(struct node *p, struct node **q) {      struct node *p_curr = p, *q_curr = *q;      struct node *p_next, *q_next;      // While therre are avialable positions in p      while (p_curr != NULL && q_curr != NULL)      {          // Save next pointers          p_next = p_curr->next;          q_next = q_curr->next;          // Make q_curr as next of p_curr          q_curr->next = p_next;  // Change next pointer of q_curr          p_curr->next = q_curr;  // Change next pointer of p_curr          // Update current pointers for next iteration          p_curr = p_next;          q_curr = q_next;     }     *q = q_curr; // Update head pointer of second list } // Driver program to test above functions int main() {      struct node *p = NULL, *q = NULL;      push(&p, 3);      push(&p, 2);      push(&p, 1);      printf("First Linked List:\n");      printList(p);      push(&q, 8);      push(&q, 7);      push(&q, 6);      push(&q, 5);      push(&q, 4);      printf("Second Linked List:\n");      printList(q);      merge(p, &q);      printf("Modified First Linked List:\n");      printList(p);      printf("Modified Second Linked List:\n");      printList(q);      getchar();      return 0; }

// C program to delete N nodes after M nodes of a linked list #include <stdio.h> #include <stdlib.h> // A linked list node struct node {     int data;     struct node *next; }; /* Function to insert a node at the beginning */ void push(struct node ** head_ref, int new_data) {     /* allocate node */     struct node* new_node = (struct node*) malloc(sizeof(struct node));     /* put in the data  */     new_node->data  = new_data;     /* link the old list off the new node */     new_node->next = (*head_ref);     /* move the head to point to the new node */     (*head_ref)  = new_node; } /* Function to print linked list */ void printList(struct node *head) {     struct node *temp = head;     while (temp != NULL)     {         printf("%d ", temp->data);         temp = temp->next;     }     printf("\n"); } // Function to skip M nodes and then delete N nodes of the linked list. void skipMdeleteN(struct node  *head, int M, int N) {     struct node *curr = head, *t;     int count;     // The main loop that traverses through the whole list     while (curr)     {         // Skip M nodes         for (count = 1; count<M && curr!= NULL; count++)             curr = curr->next;         // If we reached end of list, then return         if (curr == NULL)             return;         // Start from next node and delete N nodes         t = curr->next;         for (count = 1; count<=N && t!= NULL; count++)         {             struct node *temp = t;             t = t->next;             free(temp);         }         curr->next = t; // Link the previous list with remaining nodes         // Set current pointer for next iteration         curr = t;     } } // Driver program to test above functions int main() {     /* Create following linked list       1->2->3->4->5->6->7->8->9->10 */     struct node* head = NULL;     int M=2, N=3;     push(&head, 10);     push(&head, 9);     push(&head, 8);     push(&head, 7);     push(&head, 6);     push(&head, 5);     push(&head, 4);     push(&head, 3);     push(&head, 2);     push(&head, 1);     printf("M = %d, N = %d \nGiven Linked list is :\n", M, N);     printList(head);     skipMdeleteN(head, M, N);     printf("\nLinked list after deletion is :\n");     printList(head);     return 0; }