题解 | #合并k个已排序的链表#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
 struct ListNode* merge(struct ListNode* head1, struct ListNode* head2);
/**
 * 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 ) {
    // write code here
    struct ListNode* nHead = lists[0];
    for(int i = 1; i < listsLen; i++){
        nHead = merge(nHead, lists[i]);
    }
    return nHead;
}

struct ListNode* merge(struct ListNode* head1, struct ListNode* head2) {
    // write code here
    if(head1 == NULL){
        return head2;
    }
    if(head2 == NULL){
        return head1;
    }
    if(head1->val > head2->val){
        head2->next = merge(head1,head2->next);
        return head2;
    }else{
        head1->next = merge(head1->next,head2);
        return head1;
    }
}