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Leetcode—2.两数相加【中等】

news 2025/7/22 0:31:53

2023每日刷题（十五）

Leetcode—2.两数相加

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迭代法实现代码

/*** Definition for singly-linked list.* struct ListNode {*     int val;*     struct ListNode *next;* };*/
struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {struct ListNode* lc = (struct ListNode*)malloc(sizeof(struct ListNode));struct ListNode* p = l1;struct ListNode* q = l2;lc->next = p;int c = 0;struct ListNode* p2 = p;struct ListNode* q2 = q;while(p&&q) {c = p->val + q->val + c;int tmp = c % 10;c /= 10;p->val = tmp;if(p->next == NULL) {p2 = p;}p = p->next; q = q->next;}if(p) {while(p) {c = c + p->val;int tmp = c % 10;c /= 10;p->val = tmp;if(p->next == NULL) {p2 = p;}p = p->next;}if(c != 0) {struct ListNode* s = (struct ListNode*)malloc(sizeof(struct ListNode));s->val = c;s->next = NULL;p2->next = s;c = 0;}}if(q) {p2->next = q;while(q) {c = c + q->val;int tmp = c % 10;c /= 10;q->val = tmp;if(q->next == NULL) {q2 = q;}q = q->next;}if(c != 0) {struct ListNode* s = (struct ListNode*)malloc(sizeof(struct ListNode));s->val = c;s->next = NULL;q2->next = s;c = 0;}}if(c != 0) {struct ListNode* s = (struct ListNode*)malloc(sizeof(struct ListNode));s->val = c;s->next = NULL;p2->next = s;c = 0;}return lc->next;
}

运行结果

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递归实现代码

/*** 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 carry = 0) {if(l1 == nullptr && l2 == nullptr) {return (carry? new ListNode(carry) : nullptr);}if(l1 == nullptr) {struct ListNode* p = l1;l1 = l2;l2 = p;}carry += l1->val + (l2? l2->val: 0);l1->val = carry % 10;l1->next = addTwoNumbers(l1->next, (l2? l2->next: nullptr), carry/10);return l1;}
};