leetcode_86_Partition List - c++编程基础

Partition List
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.

class Solution {
public:
    ListNode *partition(ListNode *head, int x) {
        ListNode *first=NULL , *second=NULL , *head1=NULL , *head2=NULL;
		while(head)
		{
			if(head->val < x)
			{
				if(first == NULL)
					head1 = head;
				else
					first->next = head;
				first = head;
				//head = head->next;
			}
			else
			{
				if(second == NULL)
					head2 = head;
				else
					second->next =head;
				second = head;
				//head = head->next;
			}
			head = head->next;
		}
		if (second != NULL) {  
            second->next = NULL;  
        }  
        if (first != NULL) {  
            first->next = head2;  
            return head1;  
        }  
        else {  
            return head2;  
        }  
    }
};

#include
  
   

using namespace std;

#define N 6

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

class Solution {
public:
    ListNode *partition(ListNode *head, int x) {
        ListNode *first=NULL , *second=NULL , *head1=NULL , *head2=NULL;
		while(head)
		{
			if(head->val < x)
			{
				if(first == NULL)
					head1 = head;
				else
					first->next = head;
				first = head;
			}
			else
			{
				if(second == NULL)
					head2 = head;
				else
					second->next =head;
				second = head;
			}
			head = head->next;
		}
		if (second != NULL) {  
            second->next = NULL;  
        }  
        if (first != NULL) {  
            first->next = head2;  
            return head1;  
        }  
        else {  
            return head2;  
        }  
    }
};

ListNode *creatlist()
{
	ListNode *head=NULL;
	ListNode *p;
	for(int i=0; i
   
    >a; p = (ListNode*) malloc(sizeof(ListNode)); p->val=a; p->next = head; head = p; } return head; } int main() { ListNode *list = creatlist(); Solution lin; ListNode *outlist = lin.partition( list,3 ); for(int i=0; i
    
     val; outlist = outlist->next; } }