21. 合并两个有序链表c

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* mergeTwoLists(struct ListNode* list1, struct ListNode* list2) {
    struct ListNode* root=NULL;
    if(!list1) return list2;
    if(!list2) return list1;
    if(list1->val<list2->val){
        root=list1;
        root->next=mergeTwoLists(list1->next,list2);
    }else{
        root=list2;
        root->next=mergeTwoLists(list1,list2->next);
    }
    return root;
}

结果：