力扣2. 两数相加
/**
* 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:
/**
*
* @param l1 Given linked list l1
* @param l2 Given linked list l2
* @return ListNode*
*/
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
ListNode* p1 = l1;
ListNode* p2 = l2;
int carry = 0;
ListNode* dummy = new ListNode(666);
ListNode* tail = dummy;
if (l1 == nullptr) {
return l2;
}
if (l2 == nullptr) {
return l1;
}
while (p1 != nullptr || p2 != nullptr) {
int sum = 0;
if (p1 != nullptr) {
sum += p1 -> val;
p1 = p1 -> next;
}
if (p2 != nullptr) {
sum += p2 -> val;
p2 = p2 -> next;
}
if (carry != 0) {
sum += carry;
}
tail -> next = new ListNode(sum % 10);
carry = sum / 10;
tail = tail -> next;
}
//If carry is not equal to 0
if (carry != 0) {
tail -> next = new ListNode(carry);
}
return dummy -> next;
}
};