LeetCode Merge Two Sorted Lists C++

8363 ワード

#include <iostream>
#include <vector>
#include<algorithm>
#include <queue>
using namespace std;

/************************************************************************/
/* 
    Problem:
    Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

For example,

   Given linked list: 1->2->3->4->5, 
   Given linked list: 2->3->4->5->6;

   output:
        1-2-2-3-3-4-4-5-5-6; linklist ;
Note:


    Author  :   [email protected]

    DateTime:   2017 8 10  13:16:07

*/
/************************************************************************/





struct ListNode {
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};
class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) 
    {

        if (l1 == NULL && l2 == NULL)
            return NULL;
        ListNode *newlist = new ListNode(0);
        ListNode *head = newlist;


        while (l1 != NULL ||l2 !=NULL)
        {

            if (l2 == NULL || l1 == NULL)
            {

                if (l1 == NULL)
                {
                    head->next = l2;
                    head = head->next;
                    l2 = l2->next;
                }
                else
                {
                    head->next = l1;
                    head = head->next;
                    l1 = l1->next;

                }
                continue;
            }


            if (l1->val > l2->val)
            {
                head->next = l2;
                head = head->next;
                l2 = l2->next;
            }
            else if (l1->val < l2->val)
            {

                head->next = l1;
                head = head->next;
                l1 = l1->next;
            }
            else
            {
                head->next = l2;
                head = head->next;
                l2 = l2->next;
            }

        }
        return newlist->next;

    }
};

void main()
{

    ListNode *t1 = new ListNode(0);
    ListNode *t2 = new ListNode(0);
    ListNode *t3 = new ListNode(0);
    ListNode *t4 = new ListNode(0);
    t1->val = 4;
    t2->val = 4;
    t3->val = 4;
    t4->val = 5;
    t1->next = t2;
    t2->next = t3;
    t3->next = t4;
    ListNode *tt1 = new ListNode(0);
    ListNode *tt2 = new ListNode(0);
    ListNode *tt3 = new ListNode(0);
    ListNode *tt4 = new ListNode(0);
    tt1->val = 1;
    tt2->val = 2;
    tt3->val = 3;
    tt4->val = 4;
    tt1->next = tt2;
    tt2->next = tt3;
    tt3->next = tt4;
    Solution s1;
    ListNode  *temp = s1.mergeTwoLists(t1, tt1);


    system("pause");
    return ;
}