Algorithms/circularLinkedList at master · codeingwolf/Algorithms · GitHub

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

struct node{

	int data;
	struct node *next;
} *head= NULL;

void display(struct node *p){

	do{

		printf("%d\t", p->data);
		p= p->next;
	}while(p!= head);
}

void Rdisplay(struct node *p){

	static int flag= 0;

	if(p!= head || flag== 0){

		flag= 1;
		printf("%d\t", p->data);
		Rdisplay(p->next);
	}

	flag= 0;
}

void insert(struct node *p, int pos, int x){

	int i;

	struct node *t= (struct node*) malloc(sizeof(struct node));
	t->data= x;

	if(pos== 0){

		if(head== NULL){

			head= t;
			head->next= head;
		}

		else{

			while(p->next!= head)
				p= p->next;

			p->next= t;
			t->next= head;
			head= t;
		}
	}

	else{

		for(i= 0; i< pos-1; i++)
			p= p->next;

		t->next= p->next;
		p->next= t;
	}
}

int deleteCLL(struct node *p, int pos){

	int x, i;
	struct node *q;

	if(pos== 1){

		while(p->next!= head)
			p= p->next;

		x= head->data;

		if(p== head){
			free(head);
			head= NULL;
		}

		else{
			p->next= head->next;
			free(head);
			head= p->next;
		}
	}

	else{

		for(i= 0; i< pos-2; i++)
			p= p->next;

			q= p->next;

			p->next= q->next;
			x= q->data;
			free(q);
	}

	return x;
}

int main(){

	int pos, x, t= 5;

	while(t){

		scanf("%d %d",&pos, &x);
		insert(head, pos, x);
		Rdisplay(head);
		printf("\n\n");

		t--;
	}


	while(1){

		scanf("%d",&pos);
		x= deleteCLL(head, pos);
		printf("%d is deleted\n", x);
		display(head);
		printf("\n\n");

		t--;
	}
}