题解 | #链表相加(二)#

/**
 * struct ListNode {
 *  int val;
 *  struct ListNode *next;
 * };
 */

// 反转链表
struct ListNode* reverseList(struct ListNode* head) {
    struct ListNode* prev = NULL;
    struct ListNode* current = head;
    while (current != NULL) {
        struct ListNode* next = current->next;
        current->next = prev;
        prev = current;
        current = next;
    }
    return prev;
}

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 *
 * @param head1 ListNode类
 * @param head2 ListNode类
 * @return ListNode类
 */
struct ListNode* addInList(struct ListNode* head1, struct ListNode* head2 ) {
    // write code here
    // 反转链表
    struct ListNode* reversedHead1 = reverseList(head1);
    struct ListNode* reversedHead2 = reverseList(head2);

    struct ListNode* result = NULL;  // 存储结果的链表头节点
    struct ListNode* current = NULL; // 当前节点
    int carry = 0; // 进位

    // 遍历两个链表，进行相加操作
    while (reversedHead1 != NULL || reversedHead2 != NULL || carry != 0) {
            int sum = carry;
            if (reversedHead1 != NULL) {
                sum += reversedHead1->val;
                reversedHead1 = reversedHead1->next;
            }
            if (reversedHead2 != NULL) {
                sum += reversedHead2->val;
                reversedHead2 = reversedHead2->next;
            }

            // 创建新节点
            struct ListNode* newNode = (struct ListNode*)malloc(sizeof(struct ListNode));
            newNode->val = sum % 10;
            carry = sum / 10;
            newNode->next = NULL;

            // 连接节点
            if (result == NULL) {
                result = newNode;
                current = newNode;
            } else {
                current->next = newNode;
                current = current->next;
            }
            
    }

   
    // 反转结果链表
    result = reverseList(result);

    return result;

}