21. Merge Two Sorted Lists

[Tcdian]

21. Merge Two Sorted Lists

将两个升序链表合并为一个新的升序链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。

Example

Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4

[Tcdian]

Solution

• JavaScript Solution

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */
var mergeTwoLists = function(l1, l2) {
    let patrol1 = l1;
    let patrol2 = l2;
    let guard = new ListNode(-1);
    let patrol = guard;

    while(patrol1 !== null && patrol2!== null) {
        if (patrol1.val <= patrol2.val) {
            patrol.next = patrol1;
            patrol1 = patrol1.next;
        } else {
            patrol.next = patrol2;
            patrol2 = patrol2.next;
        }
        patrol = patrol.next;
    }

    patrol.next = patrol1 || patrol2;
    return guard.next;
};