2. 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

这道题比较简单，就是链表运用，注意进位就可以了。

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     struct ListNode *next; * }; */struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {    struct ListNode *p,*L,*q;    int carry=0;    L=malloc(sizeof(struct ListNode));    L=NULL;    p=L;    while(l1&&l2)    {        q=malloc(sizeof(struct ListNode));        q->val=(l1->val+l2->val+carry)%10;        carry=(l1->val+l2->val+carry)/10;        q->next=NULL;        if(NULL==L)            L=q;        else            p->next=q;        p=q;        l1=l1->next;        l2=l2->next;    }    while(l1)    {        q=malloc(sizeof(struct ListNode));        q->val=(l1->val+carry)%10;        carry=(l1->val+carry)/10;        q->next=NULL;        p->next=q;        p=q;        l1=l1->next;    }    while(l2)    {        q=malloc(sizeof(struct ListNode));        q->val=(l2->val+carry)%10;        carry=(l2->val+carry)/10;        q->next=NULL;        p->next=q;        p=q;        l2=l2->next;    }    if(carry)    {        q=malloc(sizeof(struct ListNode));        q->val=carry%10;        q->next=NULL;        p->next=q;        p=q;    }    return L;}