LintCode - Merge Two Sorted List

LintCode - Merge Two Sorted Lists

Web Link

http://www.lintcode.com/en/problem/merge-two-sorted-lists/

Description

Merge two sorted (ascending) linked lists and return it as a new sorted list. The new sorted list should be made by splicing together the nodes of the two lists and sorted in ascending order.
Example
Given 1->3->8->11->15->null, 2->null , return 1->2->3->8->11->15->null.

Code - C++

/** * Definition of ListNode * class ListNode { * public: *     int val; *     ListNode *next; *     ListNode(int val) { *         this->val = val; *         this->next = NULL; *     } * } */class Solution {public:    /**     * @param ListNode l1 is the head of the linked list     * @param ListNode l2 is the head of the linked list     * @return: ListNode head of linked list     */    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {        // write your code here        if (l1 == NULL) {            return l2;        }        if (l2 == NULL) {            return l1;        }        ListNode* head = l1->val < l2->val ? l1:l2;        ListNode* temp = new ListNode(0);        while (l1 != NULL && l2 != NULL) {            if (l1->val < l2->val) {                temp->next = l1;                temp = l1;                l1 = l1->next;            } else {                temp->next = l2;                temp = l2;                l2 = l2->next;            }        }        if (l1 == NULL) {            temp->next = l2;        }        if (l2 == NULL) {            temp->next = l1;        }        return head;    }};

Tips

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