219. Insert Node in Sorted Linked List【Naive】

Insert a node in a sorted linked list.

Example

Given list = 1->4->6->8 and val = 5.

Return 1->4->5->6->8.

解法一：

 /**
  * Definition of ListNode
  * class ListNode {
  * public:
  *     int val;
  *     ListNode *next;
  *     ListNode(int val) {
  *         this->val = val;
  *         this->next = NULL;
  *     }
  * }
  */

 class Solution {
 public:
     /*
      * @param head: The head of linked list.
      * @param val: An integer.
      * @return: The head of new linked list.
      */
     ListNode * insertNode(ListNode * head, int val) {
         ListNode * new_node = new ListNode(val);
         if (head == NULL) {
             return new_node;
         }

         ListNode * dummy = new ListNode(-);
         dummy->next = head;
         head = dummy;

         while (head->next != NULL) {
             if (val > head->next->val) {
                 head = head->next;
             } else {
                 new_node->next = head->next;
                 head->next = new_node;
                 break;
             }
         }

         if (head->next == NULL) {
             head->next = new_node;
         }

         return dummy->next;
     }
 };

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