LeetCode-- Add two numbers

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题目

You are given two non-empty linked lists representing two non-negative integers. 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.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

Slolution1:

struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
    typedef struct ListNode* P_ListNode  ; 
    P_ListNode   __create__node__(  int data )
    {
        P_ListNode _p   = malloc( sizeof(struct ListNode  ) ) ;  
        _p->val = data ; 
        _p->next = NULL ;
        return _p ; 
    }
    P_ListNode   p1 = l1 ; 
    P_ListNode   p2 = l2 ; 
    P_ListNode   phead = __create__node__( 0 ) ; 
    P_ListNode   pwalk = phead  ; 
    int overflow = 0; 
    while( p1 || p2 )
    {
        int vl = 0 ;
        int vr = 0 ;
        if( p1 != NULL )
        {
            vl  = p1 ->val ; 
            p1 = p1->next ; 
        }

        if( p2 != NULL )
        {
            vr = p2->val ; 
            p2 = p2->next ; 
        }
        int sum_current = vl  + vr + overflow  ; 
        pwalk ->next = __create__node__( sum_current % 10 ) ; 
        overflow  = sum_current /10 ; 
        pwalk  = pwalk ->next ; 
    }
    if(overflow  ){
        pwalk->next = __create__node__(overflow    )  ;
    }
    P_ListNode    *_tmp = phead;
    phead = phead->next ;  
    free( _tmp ) ; 
    return phead  ; 
}