Leetcode Exercise

Question:Add Two Numbers

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)

Output: 7 -> 0 -> 8

Answer

/**
* Definition for singly-linked list.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode lNode=new ListNode(0);
ListNode origin=lNode;
int carry=0;

while(l1!=null&&l2!=null){

if(l1.val+l2.val+carry<10){
lNode.val=l1.val+l2.val+carry;
carry=0;
}else{
lNode.val=(l1.val+l2.val+carry)%10;
carry=1;
}
l1=l1.next;
l2=l2.next;
if(l1!=null&&l2!=null){
lNode.next=new ListNode(0);
lNode=lNode.next;
}

}

if(l1==null&&l2==null){
if(carry==0){
return origin;
}else{
lNode.next=new ListNode(1);
lNode=null;
}
}

if(l1!=null){
lNode.next=new ListNode(0);
lNode=lNode.next;
while(l1!=null){
if(l1.val+carry<10){
lNode.val=l1.val+carry;
carry=0;
}else{
lNode.val=(l1.val+carry)%10;
carry=1;
}

l1=l1.next;
if(l1!=null){
lNode.next=new ListNode(0);
lNode=lNode.next;
}
}
if(carry==1){
lNode.next=new ListNode(1);
lNode=null;
}
}

if(l2!=null){
lNode.next=new ListNode(0);
lNode=lNode.next;
while(l2!=null){
if(l2.val+carry<10){
lNode.val=l2.val+carry;
carry=0;
}else{
lNode.val=(l2.val+carry)%10;
carry=1;
}

l2=l2.next;
if(l2!=null){
lNode.next=new ListNode(0);
lNode=lNode.next;
}
}
if(carry==1){
lNode.next=new ListNode(1);
lNode=null;
}
}

return origin;
}

}