题解 | #两个链表生成相加链表#

class Solution {
public:
    /**
     * 
     * @param head1 ListNode类 
     * @param head2 ListNode类 
     * @return ListNode类
     */

    ListNode* addInList(ListNode* head1, ListNode* head2) {
        // write code here
        stack<int> l1,l2;
        if(head1==nullptr) return head2;
        else if(head2==nullptr) return head1;
        while(head1 || head2)
        {
            if(head1) {l1.push(head1->val);head1 = head1->next;}
            if(head2) {l2.push(head2->val);head2 = head2->next;}
        }
        ListNode* res=nullptr;
        int canny=0;
        int num1 = min(l1.size(),l2.size());
        int num2 = labs(l1.size()-l2.size());
        for(int i=0;i<num1;i++)
        {
            canny += l1.top()+l2.top();
            l1.pop();
            l2.pop();
            ListNode* cur= new ListNode(canny%10);
            canny = canny/10;
            cur->next = res;
            res = cur;
        }
        for(int i=0;i<num2;i++)
        {
            canny += l1.size()==0 ? l2.top() : l1.top();
            l1.size()==0 ? l2.pop() : l1.pop();
            ListNode* cur= new ListNode(canny%10);
            canny = canny/10;
            cur->next = res;
            res = cur;
        }
        if(canny>0)
        {
            ListNode* cur= new ListNode(canny);
            cur->next = res;
            res = cur;
        }
        return res;
    }
};