[Linked List]Insertion Sort List

Total Accepted: 59422 Total Submissions: 213019 Difficulty: Medium

 

Sort a linked list using insertion sort.

 (M) Sort List

 

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* insertionSortList(ListNode* head) {
        if(head==NULL || head->next==NULL){
            return head;
        }
        ListNode* cur = head->next,*cur_pre=head,*cur_next=NULL;
        while(cur){
            cur_next = cur->next;
            
            /* 当前值小于前驱值，该节点需要重新调整 */
            if(cur->val < cur_pre->val){
                ListNode* insert_node_pre = NULL,*insert_node=head;
                while(cur->val > insert_node->val){
                    insert_node_pre = insert_node;
                    insert_node = insert_node->next;
                }
                insert_node_pre ? insert_node_pre->next = cur : head = cur;
                cur->next = insert_node;
                cur_pre->next = cur_next;
            }else{
                cur_pre = cur;
            }
            
            cur = cur_next;
        }
        return head;
    }
};

Next challenges: (M) Reorder List (M) H-Index (H) Best Meeting Point