[LeetCode OJ] Insertion Sort List 解题报告

来源：互联网发布：代工上淘宝好吗编辑：程序博客网时间：2024/05/21 17:24

地址:https://oj.leetcode.com/problems/insertion-sort-list/

题意:链表的插入排序

注意:所有和指针有关的代码都要非常注意边界处理。

要点:理解链表和数组的插入排序的不同，插入时链表不需要向后或向前移动，比数组的插入排序要快，但复杂度还是O(N2)。

#include <iostream>#include <stack>#include <string>#include <vector>#include <cstdlib>using namespace std;/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:void insertNode(ListNode *head,ListNode *node){    ListNode *ptr = head->next;    ListNode *pre = head;    bool flag = 0;    while(ptr != NULL){        if(ptr->val > node->val){            pre->next = node;            node->next = ptr;            flag = 1;            break;        }        pre = ptr;        ptr = ptr->next;    }    if(flag == 0){        pre->next = node;        node->next = NULL;    }}ListNode *insertionSortList(ListNode *head) {    if(!head||!head->next) return head;    ListNode L(0);    ListNode *List = &L;    ListNode *ptr = head;    ListNode *node = NULL;    while(ptr!=NULL){        node = ptr;        ptr = ptr->next;        insertNode(List,node);    }    return List->next;}};

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