leetcode c++ 简单题之两数相加

个人解答
class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
ListNode *head = new ListNode(-1);
ListNode *p = head;
int sum = 0;
int temp;
int flag=0;
int n1,n2;
while(l1 || l2){
n1 = l1?l1->val:0;
n2 = l2?l2->val:0;
temp = n1 + n2 + flag;
p->next = new ListNode(temp % 10);
flag = temp / 10;
p = p->next;
l1?l1 = l1->next:l1 = l1;
l2?l2 = l2->next:l2 = l2;
}
if(flag){
p->next = new ListNode(flag);
}
return head->next;
}
};

官方答案
class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
ListNode *head = nullptr, *tail = nullptr;
int carry = 0;
while (l1 || l2) {
int n1 = l1 ? l1->val: 0;
int n2 = l2 ? l2->val: 0;
int sum = n1 + n2 + carry;
if (!head) {
head = tail = new ListNode(sum % 10);
} else {
tail->next = new ListNode(sum % 10);
tail = tail->next;
}
carry = sum / 10;
if (l1) {
l1 = l1->next;
}
if (l2) {
l2 = l2->next;
}
}
if (carry > 0) {
tail->next = new ListNode(carry);
}
return head;
}
};
作者:LeetCode-Solution
链接:https://leetcode-cn.com/problems/add-two-numbers/solution/liang-shu-xiang-jia-by-leetcode-solution/
来源:力扣(LeetCode)
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个人总结
- 创建头节点便于后面的操作
- 刚开始用老实人办法即把节点数转换为实数相加后再用链表分别装,但是当遇到很大的数字的时候就会溢出,尝试过long long、float等,都不太管用,看了评论区才开始尝试逐位相加