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2-add-two-numbers.cpp
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2-add-two-numbers.cpp
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/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode() : val(0), next(nullptr) {}
* ListNode(int x) : val(x), next(nullptr) {}
* ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
int CY=0; // carry
auto head = l1, prev=l1;
while(l1 && l2)
l1->val += l2->val+CY, CY=l1->val/10, l1->val%=10, prev=l1, l1=l1->next, l2=l2->next;
if(l2) prev->next=l2; // if l2 longer than l1
while(l2) l2->val+=CY, CY=l2->val/10, l2->val%=10, prev=l2, l2=l2->next; // if l2 longer than l1
while(l1) l1->val+=CY, CY=l1->val/10, l1->val%=10, prev=l1, l1=l1->next; // if l1 longer than l2
if(CY) prev->next=new ListNode(CY);
return head;
}
};