题解 | #合并k个已排序的链表#

/**
 * struct ListNode {
 *  int val;
 *  struct ListNode *next;
 * };
 */
/**
 * 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 lists ListNode类一维数组
 * @param listsLen int lists数组长度
 * @return ListNode类
 */
struct ListNode* mergeKLists(struct ListNode** lists, int listsLen ) {
    if (listsLen == 1 | listsLen == 0) {
        return lists[0];
    }
    int a = listsLen - 1;
    struct ListNode* list1 = lists[a - 1], *list2 = lists[a];
    struct ListNode* sum = malloc(sizeof(struct ListNode));
    struct ListNode* H = sum;
    while (1) {
        if (list1 == NULL) {
            sum->next = list2;
            break;
        } else if (list2 == NULL) {
            sum->next = list1;
            break;
        } else if (list1->val < list2->val) {
            sum->next = list1;
            list1 = list1->next;
            sum = sum->next;
            if (list1 == NULL) {
                sum->next = list2;
                break;
            }
        } else {
            sum->next = list2;
            list2 = list2->next;
            sum = sum->next;
            if (list2 == NULL) {
                sum->next = list1;
                break;
            }
        }
    }
    lists[a - 1] = H->next;
    return mergeKLists(lists, a);
}