[Leetcode]21.merge Sorted Lists

"title"

Merge sorted linked lists and return it as a new list. The new list should is made by splicing together the nodes of the first of the lists.

"Analysis"

No

"Code"

/********************************** Date: 2015-01-06* sjf0115* title: 21.Merge, Sorted lists* Source: Https://oj.leetcode. com/problems/merge-two-sorted-lists/* Result: ac* Source: leetcode* Blog: **********************************/#include <    iostream>using namespace std;struct listnode{int val;    ListNode *next;        ListNode (int x): Val (x), Next (NULL) {}};class solution {Public:listnode *mergetwolists (ListNode *l1, ListNode *l2) {        ListNode *head = new ListNode (-1);        ListNode *p1 = L1,*P2 = L2,*cur = head;                while (P1 = null && P2! = null) {//Take two smaller elements of the list header if (P1->val < P2->val) {                Cur->next = p1;            P1 = p1->next;                }//if else{cur->next = p2;            P2 = p2->next;        }//else cur = cur->next;            }//while//If the list 1 is not finished traversing while (p1) {cur->next = P1;            P1 = p1->next; Cur = cur-> next;            }//while//If the list 2 is not finished traversing while (p2) {cur->next = p2;            P2 = p2->next;        Cur = cur->next;        }//while cur->next = NULL;    Return head->next;    }};int Main () {solution solution;    int a[] = {1,2,4,7,9};    int b[] = {3,5,8,10,11,12};    List 1 ListNode *head1 = new ListNode (a[0]);    ListNode *p1 = head1;        for (int i = 1;i < 5;i++) {ListNode *node = new ListNode (A[i]);        P1->next = node;    p1 = node;    }//for//List 2 ListNode *head2 = new ListNode (b[0]);    ListNode *p2 = head2;        for (int i = 1;i < 6;i++) {ListNode *node = new ListNode (B[i]);        P2->next = node;    p2 = node;    }//for ListNode *head = solution.mergetwolists (head1,head2);    Output ListNode *p = head;        while (p) {cout<<p->val<< "";    p = p->next; }//while Cout<<endl;}

"Code Two"

Recursive implementation

Class Solution {public:    listnode *mergetwolists (ListNode *l1, ListNode *l2) {        if (L1 = = NULL) return l2;        if (L2 = = NULL) return L1;        if (L1->val < L2->val) {            L1->next = mergetwolists (L1->next, L2);            return L1;        } else {            L2->next = mergetwolists (L2->next, L1);            return l2;}}    ;

[Leetcode]21.merge Sorted Lists