Thread: addition of linkedList

There are two linked List, each node of the list carrying a digit. Write program to add these two linked list and create a third list with the result value
e.g:
1st List : 1->2->3->4->NULL
2nd List : 3->4->5->6->NULL

Resultant List : 4->6->9->0->NULL

Code:

struct linkedList {
	int data;
	struct linkedList* next;
};

typedef struct linkedList* List;

List addList(List L1, List L2)
{
	int carry = 0,sum=0;
	List L3 = NULL, tmp, bkp, rest = NULL;
	if(!L1 && !L2)
		return NULL;
	if(!L1)
		return L2;
	if(!L2)
		return L1;
	L1 = reverseList(L1); 
	L2 = reverseList(L2);
	while(L1 && L2) {
		sum = L1->data + L2->data + carry;
		carry = sum/10;
		sum = sum%10;
		tmp = (List) malloc(sizeof(struct linkedList));
		tmp->data = sum;
		tmp->next = NULL;

		if(!L3)
			bkp = L3 = tmp;
		else {
			L3->next = tmp;
			L3 = L3->next;
		}
		L1 = L1->next;
		L2 = L2->next;
	}
	if (L1)
		rest = L1;
	else if (L2)
		rest = L2;
	while(carry) {
		if(rest) {
			sum = carry + rest->data;
			carry = sum/10;
			L3->next = (List) malloc(sizeof(struct linkedList));
			L3->next->data = sum%10;
			L3 = L3->next;
			rest = rest->next;
		} else {
			L3->next = (List) malloc(sizeof(struct linkedList));
			L3->next->data = carry;
			L3->next->next = NULL;
			carry = 0;
		}
	}
	bkp = reverseList(bkp);
	return bkp;
}

#include<iostream.h>
#include<conio.h>
struct list1
{
int num;
list1 *next;
}*start1,*rear1,*newptr1,*ptr1;
struct list2
{
int num;
list2 *next;
}*start2,*rear2,*newptr2,*ptr2;
struct list3
{
int num;
list3 *next;
}*start3,*rear3,*ptr3;
list1 *createNewList1(int);
list2 *createNewList2(int);
list3 *createNewList3(int);
void insertNewList1(list1 *);
void insertNewList2(list2 *);
void insertNewList3(list3 *);
void main()
{
int choice,number=0;
char ans;
do
{
clrscr();
cout<<"Welcome to linked list program.\n";
cout<<"1. Enter numbers in list 1.\n";
cout<<"2. Enter numbers in list 2.\n";
cout<<"3. Add numbers from list 1 and list 2 sequentially into list 3.\n";
cout<<"4. Display list 1.\n";
cout<<"5. Display list 2.\n";
cout<<"6. Display list 3.\n";
cout<<"7. Exit\n";
cout<<"Enter choice:";
cin>>choice;
switch(choice)
{
case 1:
do
{
cout<<"Enter the number:";
cin>>number;
newptr1=createNewList1(number);
insertNewList1(newptr1);
cout<<"\nWant to enter more numbers(y or n):";
cin>>ans;
}
while(ans=='y');
break;
case 2:
do
{
cout<<"Enter the number:";
cin>>number;
newptr2=createNewList2(number);
insertNewList2(newptr2);
cout<<"Want to enter more numbers(y or n):";
cin>>ans;
}
while(ans=='y');
break;
case 3:
ptr1=start1;ptr2=start2;
while(ptr1!=NULL && ptr2!=NULL)
{
int num=ptr1->num+ptr2->num;
num=num;
list3 *newptr=createNewList3(num);
insertNewList3(newptr);
ptr1=ptr1->next;
ptr2=ptr2->next;
}
break;
case 4:
clrscr();
ptr1=start1;
while(ptr1!=NULL)
{
cout<<ptr1->num<<"->";
ptr1=ptr1->next;
}
getch();
break;
case 5:
clrscr();
ptr2=start2;
while(ptr2!=NULL)
{
cout<<ptr2->num<<"->";
ptr2=ptr2->next;
}
getch();
break;
case 6:
clrscr();
ptr3=start3;
while(ptr3!=NULL)
{
cout<<ptr3->num<<"->";
ptr3=ptr3->next;
}
getch();
break;
case 7:
break;
default:
cout<<"Enter only 1-7";
break;
}
}
while(choice!=7);
}
list1 *createNewList1(int num)
{
list1 *ptr=new list1();
ptr->num=num;
ptr->next=NULL;
return ptr;
}
list2 *createNewList2(int num)
{
list2 *ptr=new list2();
ptr->num=num;
ptr->next=NULL;
return ptr;
}
list3 *createNewList3(int num)
{
list3 *ptr=new list3();
ptr->num=num;
ptr->next=NULL;
return ptr;
}
void insertNewList1(list1 *ptr)
{
if(start1==NULL)
{
start1=rear1=ptr;
return;
}
rear1->next=ptr;
rear1=ptr;
}
void insertNewList2(list2 *ptr)
{
if(start2==NULL)
{
start2=rear2=ptr;
return;
}
rear2->next=ptr;
rear2=ptr;
}
void insertNewList3(list3 *ptr)
{
if(start3==NULL)
{
start3=rear3=ptr;
return;
}
rear3->next=ptr;
rear3=ptr;
}