21. Merge Two Sorted Lists

BF

实现

遍历两个链表，存进数组，排序，生成新链表

提示I - One Pass

实现

/**
 * 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) {
  const dummy = new ListNode(0);
  let last = dummy;
  
  while (l1 !== null && l2 !== null) {
    if (l1.val < l2.val) {
      last.next = l1;
      l1 = l1.next;
    } else {
      last.next = l2;
      l2 = l2.next;
    }
    last = last.next;
  }
  
  if (l1 === null) last.next = l2;
  if (l2 === null) last.next = l1;
  
  return dummy.next;
};