/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
ListNode * p1 = l1;
ListNode * p2 = l2;
ListNode * dummy = new ListNode(0);
ListNode * p3 = dummy;
int sum = 0;
int carry = 0;
while(l1 != nullptr || l2 != nullptr){
if (l1 != nullptr){
sum += l1->val;
l1 = l1->next;
}
if (l2 != nullptr){
sum += l2->val;
l2 = l2->next;
}
sum += carry;
if (sum >= 10){
sum -= 10;
carry = 1;
}
else
carry = 0;
p3->next = new ListNode(sum);
sum = 0;
p3 = p3->next;
}
if (carry == 1)
p3->next = new ListNode(1);
return dummy->next;
}
};
Mistakes:
- Sum the boundary is >= 10, or > 9. Do not write > 10...
- Using two lists are better than using one list and iterate on it...
- Remember to reset sum every time you move to a new position.
- Sum the boundary is >= 10, or > 9. Do not write > 10...
- Using two lists are better than using one list and iterate on it...
- Remember to reset sum every time you move to a new position.
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