双指针
2. 两数相加：基础题，模拟加法计算过程，注意补位与进位即可，代码如下：
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| class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
ListNode* dummy = new ListNode();
ListNode* p = new ListNode();
ListNode* q = new ListNode();
dummy->next = p;
ListNode* p1 = l1, *p2 = l2;
while(p1->next != nullptr || p2->next != nullptr) {
if (p1->next == nullptr && p2->next != nullptr) p1->next = new ListNode(0);
if (p2->next == nullptr && p1->next != nullptr) p2->next = new ListNode(0);
p1 = p1->next;
p2 = p2->next;
}
p1 = l1, p2 = l2;
bool carray = false;
while (p1 != nullptr) {
int num = 0;
if (carray) {
num = p1->val + p2->val + 1;
}
else {
num = p1->val + p2->val;
}
p->val = num%10;
if (num >= 10) carray = true;
else carray = false;
p1 = p1->next;
p2 = p2->next;
p->next = new ListNode();
q = p;
p = p->next;
}
if (carray) p->val = 1;
else {
q->next = nullptr;
}
return dummy->next;
}
};
|