链式A+B

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Plus:
    def plusAB(self, a, b):
        # write code here
        s=ListNode(0)
        h=s
        c=0
        while a!=None or b!=None:
            s.next=ListNode(0)
            s=s.next
            if a==None:
                na=0
            else:
                na=a.val
                a=a.next
            if b==None:
                nb=0
            else:
                nb=b.val
                b=b.next
            s.val=(na+nb+c)%10#要考虑进位
            c=int((na+nb+c)/10)
        if c>0:
            s.next=ListNode(0)
            s=s.next
            s.val=c
        return h.next
            

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};*/
class Plus {
public:
    ListNode* plusAB(ListNode* a, ListNode* b) {
        // write code here
        ListNode* Head=new ListNode(-1);
        ListNode* p=Head;
        ListNode* node=nullptr;
        int c=0,sum,val_a,val_b;
        ListNode* pa=a,*pb=b;
        while(pa!=nullptr || pb!=nullptr || c!=0){
            val_a=(pa==nullptr?0:pa->val);
            val_b=(pb==nullptr?0:pb->val);
            sum=val_a+val_b+c;
            c=sum/10;
            node=new ListNode(sum%10);
            p->next=node;
            p=node;
            pa=(pa==nullptr?nullptr:pa->next);
            pb=(pb==nullptr?nullptr:pb->next);
        }
        return Head->next;
    }
};