Partition List

单词：partition 分割
说明：
Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater
than or equal to x.
You should preserve the original relative order of the nodes in each of the two partitions.
For example, Given 1->4->3->2->5->2 and x = 3, return 1->2->2->4->3->5.

#include <stdio.h>
#include <stdlib.h>
typedef struct _LinkNode{
    int data;
    struct _LinkNode *next;
}LinkNode;
typedef struct _LinkList{
    LinkNode *head;
    int length;
}LinkList;
//初始化
LinkList *Init()
{
    //创建链表
    LinkList *list=(LinkList*)malloc(sizeof(LinkList));
    //创建链表节点
    LinkNode *node=(LinkNode*)malloc(sizeof(LinkNode));
    //初始化
    list->head=node;
    node->data=0;
    node->next=NULL;
    list->length=0;
    return list;
}
//插入
void Insert(LinkList *list,int pos,int data)
{
    //合法性检验
    if(list==NULL)
        return ;
    if(pos>list->length)
        pos=list->length;
    //创建辅助节点
    LinkNode *pCurrent=list->head;
    //找到pos的前一个位置
    int i=0;
    for(i=0;i<pos;i++)
    {
        pCurrent=pCurrent->next;
    }
    //创建新节点
    LinkNode *newnode=(LinkNode*)malloc(sizeof(LinkNode));
    newnode->data=data;
    newnode->next=NULL;
    //插入节点
    newnode->next=pCurrent->next;
    pCurrent->next=newnode;
    list->length++;
}
//打印
void Print(LinkList* list)
{
    //合法性检验
    if(list==NULL)
        return;
    //创建辅助节点
    LinkNode *pCurrent=list->head->next;
    //遍历打印
    int i=0;
    for(i=0;i<list->length;i++)
    {
        printf("%2d",pCurrent->data);
        pCurrent=pCurrent->next;
    }
}
//链表释放
void Free(LinkList *list)
{
    if(list==NULL)
        return;
    //创建辅助接点
    LinkNode *pCurrent=list->head->next;
    LinkNode *now=NULL;
    while(pCurrent!=NULL)
    {
        now=pCurrent->next;
        free(pCurrent);
        pCurrent=now;
    }
    list->head->next=NULL;
    list->length=0;
}
//销毁链表
void Destroy(LinkList *list)
{
    if(list==NULL)
        return;
    Free(list);
    if(list->head!=NULL)
        free(list->head);
    free(list);
}
//分割链表，小于data的节点在左边，大于或等于data的节点在右边，分割两段的原顺序保存不变
void Partition(LinkList *list,LinkList *llist1,int data)
{
    //辅助接点
    LinkNode *pCurrent=list->head->next;
    //辅助链表
    LinkList *rlist1=Init();
    //遍历，把小于data节点数据存入链表llist1，不小于的存入临时链表rlist1；
    while(pCurrent!=NULL)
    {
        if(pCurrent->data < data)
        {
            Insert(llist1,llist1->length,pCurrent->data);
        }
        if(pCurrent->data >= data)
        {
            Insert(rlist1,rlist1->length,pCurrent->data);
        }
        pCurrent=pCurrent->next;

    }
    //遍历，将临时链表的数据存入链表llist1
    pCurrent=rlist1->head->next;
    while(pCurrent!=NULL){
        Insert(llist1,llist1->length,pCurrent->data);
        pCurrent=pCurrent->next;
    }
    //销毁临时链表
    Destroy(rlist1);
}
int main()
{
    //创建链表
    LinkList *list=Init();
    LinkList *list1=Init();
    //插入数据
    Insert(list,0,2);
    Insert(list,0,5);
    Insert(list,0,2);
    Insert(list,0,3);
    Insert(list,0,4);
    Insert(list,0,1);
    //打印
    Print(list);
    printf("\n");
    //分割链表
    Partition(list,list1,3);
    Print(list1);
    //销毁链表
    Destroy(list);
    Destroy(list1);

    return 0;
}