题解 | #链表相加(二)#

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head1 ListNode类 
     * @param head2 ListNode类 
     * @return ListNode类
     */
    ListNode* dz(ListNode* head){
        if(head->next==nullptr){
            return head;
        }
        ListNode *p=head;
        ListNode *f=head->next;
        ListNode *r=f->next;
        p->next=nullptr;
        while(r!=nullptr){
            f->next=p;
            p=f;
            f=r;
            r=r->next;
        }
        f->next=p;
        return f;
    }
    ListNode* addInList(ListNode* head1, ListNode* head2) {
        if(head1==nullptr){
            return head2;
        }
        if(head2==nullptr){
            return head1;
        }
        ListNode *h1=dz(head1);
        ListNode *h2=dz(head2);
        int h=0;
        ListNode *ans=new ListNode(h1->val+h2->val);
        ListNode *a=ans;
        if(ans->val>9){
            h=1;
            ans->val-=10;
        }
        h1=h1->next;
        h2=h2->next;
        while(h1!=nullptr&&h2!=nullptr){
            ListNode *t=new ListNode(h1->val+h2->val+h);
            h=0;
            ans->next=t;
            ans=ans->next;
            if(ans->val>9){
                h=1;
                ans->val-=10;
            }
            h1=h1->next;
            h2=h2->next;
        }
        while(h1!=nullptr){
            ListNode *t=new ListNode(h1->val+h);
            h=0;
            ans->next=t;
            ans=ans->next;
            if(ans->val>9){
                h=1;
                ans->val-=10;
            }
            h1=h1->next;
        }
        while(h2!=nullptr){
            ListNode *t=new ListNode(h2->val+h);
            h=0;
            ans->next=t;
            ans=ans->next;
            if(ans->val>9){
                h=1;
                ans->val-=10;
            }
            h2=h2->next;
        }
        if(h==1){
            ListNode *t=new ListNode(h);
            h=0;
            ans->next=t;
        }
        ListNode *head=dz(a);
        return head;
    }
};