面试金典--以x为基准对链表进行划分

题目描述：以给定值x为基准将链表分割成两部分，所有小于x的节点排在大于等于x的节点之前。

思路：设置largehead,largetail和smallhead,smalltail，第一次找到小于或者大于等于x的节点时就更新head指针，后面遍历链表每次更新tail指针。

实现没考虑空链表等边界情况。

#include <iostream>
#include <string>
#include <fstream>
#include <map>
#include <algorithm>
#include <vector>
#include <ctime>
#include <bitset>

using namespace std;

template<typename T>
class Node
{
public:
    Node<T> *next;
    T data;

    Node(T d):data(d),next(NULL){}
    void appendToTail(T d)
    {
        Node<T> *end = new Node<T>(d);
        Node<T> *n = this;
        while(n->next != NULL)
        {
            n = n->next;
        }
        n->next = end;
    }
};

int main()
{
    Node<int> *head = new Node<int>(1);
    int i;
    head->appendToTail(4);
    for(i = 2 ; i < 6 ; ++i)
    {
        head->appendToTail(i);
    }
    //2.4
    head->appendToTail(4);
    head->appendToTail(3);
    Node<int> *largeHead = NULL;
    Node<int> *largeTail = NULL;
    Node<int> *smallHead = NULL;
    Node<int> *smallTail = NULL;
    Node<int> *headOrg = head;
    int x = 3;
    while(head != NULL)
    {
        if(head->data >= x)
        {
            if(largeHead == NULL)
            {
                largeHead = head;
                largeTail = head;
            }
            else
            {
                largeTail->next = head;
                largeTail = head;
            }
        }
        else
        {
            if(smallHead == NULL)
            {
                smallHead = head;
                smallTail = head;
            }
            else
            {
                smallTail->next = head;
                smallTail = head;
            }
        }
        head = head->next;
    }
    smallTail->next = largeHead;
    while(smallHead != NULL)
    {
        cout<<smallHead->data<<endl;
        smallHead = smallHead->next;
    }
    return 0;
}