题解 | 链表相加(二)

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 *	ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
class Solution {
public:
    ListNode* reNode(ListNode* node) {
        ListNode* pre = nullptr;
        ListNode* cur = node;
        while (cur) {
            ListNode* nxt = cur->next;
            cur->next = pre;
            pre = cur;
            cur = nxt;
        }
        return pre;
    }
    ListNode* addInList(ListNode* head1, ListNode* head2) {
        head1 = reNode(head1);
        head2 = reNode(head2);
        int add = 0;
        ListNode* dummyNode = new ListNode(0);
        ListNode* node = dummyNode;
        ListNode* node1 = head1;
        ListNode* node2 = head2;
        while (node1&&node2) {
            int sum = add + node1->val + node2->val;
            add = sum/10;
            sum = sum%10;
            node->next = new ListNode(sum);
            node = node->next;
            node1 = node1->next;
            node2 = node2->next;
        }
        ListNode* lef_node = node1?node1:node2;
        while(lef_node) {
            int sum = add + lef_node->val;
            add = sum/10;
            sum %=10;
            node->next = new ListNode(sum);
            node = node->next;
            lef_node = lef_node->next;
        }
        if (add) {
            node->next = new ListNode(add);
        }
        ListNode* to_res = dummyNode->next;
        to_res = reNode(to_res);

        return to_res;
    }
};