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# Add Two Numbers

## 原文

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

## C++

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
int carry=0;
ListNode* listNode=new ListNode(0);
ListNode* p1=l1,*p2=l2,*p3=listNode;

while(p1!=NULL|p2!=NULL)
{
if(p1!=NULL)
{
carry+=p1->val;
p1=p1->next;
}
if(p2!=NULL)
{
carry+=p2->val;
p2=p2->next;
}
p3->next=new ListNode(carry%10);
p3=p3->next;
carry/=10;
}
if(carry==1)
p3->next=new ListNode(1);
return listNode->next;
}
};

## c

/**
* Definition for singly-linked list.
* public class ListNode {
*     public int val;
*     public ListNode next;
*     public ListNode(int x) { val = x; }
* }
*/
public class Solution
{
public ListNode AddTwoNumbers(ListNode l1, ListNode l2)
{
int carry = 0;
ListNode listNode= new ListNode(0);
ListNode p1 = l1, p2 = l2, p3 = listNode;

while (p1 != null || p2 != null)
{
if (p1 != null)
{
carry += p1.val;
p1 = p1.next;
}
if (p2 != null)
{
carry += p2.val;
p2 = p2.next;
}
p3.next = new ListNode(carry % 10);
p3 = p3.next;
carry /= 10;
}
if (carry == 1)
p3.next = new ListNode(1);
return listNode.next;
}
}

## Java

public class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
int carry=0;
ListNode listNode=new ListNode(0);
ListNode p1=l1,p2=l2,p3=listNode;
while(p1!=null||p2!=null){
if(p1!=null){
carry+=p1.val;
p1=p1.next;
}
if(p2!=null){
carry+=p2.val;
p2=p2.next;
}
p3.next=new ListNode(carry%10);
p3=p3.next;
carry/=10;
}
if(carry==1)
p3.next=new ListNode(1);
return listNode.next;
}
}

## C++（来源于网络）

class Solution {
public:
ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
int carry=0;
ListNode* res=new ListNode(0);
ListNode* head = res;
while (l1 && l2){
res->next=new ListNode((l1->val+l2->val+carry)%10);
carry = (l1->val+l2->val+carry)/10;
l1=l1->next;
l2=l2->next;
res=res->next;
}
while (l1){
res->next=new ListNode((l1->val+carry)%10);
carry = (l1->val+carry)/10;
l1=l1->next;
res=res->next;
}
while (l2){
res->next=new ListNode((l2->val+carry)%10);
carry = (l2->val+carry)/10;
l2=l2->next;
res=res->next;
}
if (carry>0){
res->next = new ListNode(carry);
}
return head->next;
}
};