leetcode

题目：Insertion Sort List

Sort a linked list using insertion sort.

题目比较简单，就是对链表进行插入排序

个人思路：

1，用插入排序的方法来解就行，注意链表的处理，可以给原链表加个头结点来使得处理统一（我的代码没有加，懒得改了）

代码：

#include <stddef.h>

struct ListNode
{
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {};
};

class Solution {
public:
    ListNode *insertionSortList(ListNode *head) {
        if (!head)
        {
            return NULL;
        }

        ListNode *current = head->next;
        ListNode *currentBefore = head;
        ListNode *find = NULL;
        ListNode *findBefore = NULL;

        while (current)
        {
            find = head;
            while (find != current)
            {
                if (current->val < find->val)
                {
                    if (find == head) //当前结点小于头结点
                    {
                        currentBefore->next = current->next;
                        current->next = find;
                        head = current;
                        current = currentBefore->next;
                        break;
                    }
                    else
                    {
                        currentBefore->next = current->next;
                        current->next = find;
                        findBefore->next = current;
                        current = currentBefore->next;
                        break;
                    }
                }
                findBefore = find;
                find = find->next;
            }
            if (find == current) //当前结点比前面结点都大，没有对链表做任何改变
            {
                currentBefore = current;
                current = current->next;
            }
        }

        return head;
    }
};

网上的思路基本是一样的