C code for finding merge point of two linked lists

//finding the merge point of two lists

//list1 contains 10,15,30

//list 2 contains 3,6,9,15,30 such that

//15 in both the lists are stored in same location ie merge point

/*ALGO:

-count the list1 say c1

-count the list2 say c2

-absoulte difference say d

-traverse the longer list by d nodes

-then traverse both the lists simueltaeously

-when two nodes gets equal in address that is point of merge

*/

#include<stdio.h>

#include<stdlib.h>

struct node

{

int data;

struct node *next;

};

void display(struct node *head1);

int countNode(struct node *head1);

int mergePoint(struct node *head1,struct node *head2,int d);

int main()

{

struct node *head1=(struct node *)malloc(sizeof(struct node));

head1->data=10;

head1->next=NULL;

struct node *head2=(struct node *)malloc(sizeof(struct node));

head2->data=3;

head2->next=NULL;

struct node *newnode=(struct node *)malloc(sizeof(struct node));

newnode->data=6;

head2->next=newnode;

newnode=(struct node *)malloc(sizeof(struct node));

newnode->data=9;

head2->next->next=newnode;

newnode=(struct node *)malloc(sizeof(struct node));

newnode->data=15;

head2->next->next->next=newnode;

head1->next=newnode;

printf("head2->next->next->next=newnode=%p\n",head2->next->next->next);

printf("head1->next=%p\n",head1->next);

newnode=(struct node *)malloc(sizeof(struct node));

newnode->data=30;

head1->next->next=newnode;

//head2->next->next->next->next=newnode;

head1->next->next->next=NULL;

display(head1);

printf("\n");

display(head2);

printf("\n");

int c1,c2,d;

c1=countNode(head1);

printf("\n");

c2=countNode(head2);

printf("\n");

if(c1>c2)

{

d=c1-c2;

printf("d=c1=%d\n",d);

}

else

{

d=c2-c1;

printf("d=c2=%d\n",d);

}

int t=0;

t=mergePoint(head1,head2,d);

printf("Merege point is at node:%d\n",t);

return 0;

}

//function to display the nodes

void display(struct node *h)

{

struct node *current=h;

while(current!=NULL)

{

printf("%d ",current->data);

current=current->next;

}

}

//function to count the nodes

int countNode(struct node *h)

{

int count=0;

struct node *current=h;

while(current!=NULL)

{

count=count+1;

current=current->next;

}

printf("size of list1=%d\n",count);

return count;

}

//function to give the merge point

int mergePoint(struct node *head1,struct node *head2,int d)

{

int i;

struct node *current1=head1;

struct node *current2=head2;

for(i=0;i<d;i++)

{

printf("i=%d,current2->data=%d\n",i,current2->data);

current2=current2->next;

}

while(current1!=NULL && current2!=NULL)

{

printf("while=\n");

if(current1==current2)

{

printf("\n\ncurrent1->data====%d\n\n",current1->data);

return current1->data;

}

current1=current1->next;

current2=current2->next;

}

}

/*OUTPUT:

head2->next->next->next=newnode=0x9dc7048

head1->next=0x9dc7048

10 15 30

3 6 9 15 30

size of list1=3

size of list1=5

d=c2=2

i=0,current2->data=3

i=1,current2->data=6

while=

while=

current->data====15

Merege point is at node:15*/