21.合并两个有序链表.md

题目

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/merge-two-sorted-lists
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */
var mergeTwoLists = function (l1, l2) {
  if (!l1) {
    return l2
  } else if (!l2) {
    return l1
  } else if (l1.val < l2.val) {
    l1.next = mergeTwoLists(l1.next, l2)
    return l1
  } else {
    l2.next = mergeTwoLists(l2.next, l1)
    return l2
  }
}

Test

    var l1 = {
      val: 1,
      next: {
        val: 2,
        next: {
          val: 4,
          next: null
        }
      }
    }
    var l2 = {
      val: 1,
      next: {
        val: 3,
        next: {
          val: 4,
          next: null
        }
      }
    }
    var mergeTwoLists = function (l1, l2) {
      if (!l1) {
        return l2
      } else if (!l2) {
        return l1
      } else if (l1.val < l2.val) {
        l1.next = mergeTwoLists(l1.next, l2)
        return l1
      } else {
        l2.next = mergeTwoLists(l2.next, l1)
        return l2
      }
    }
    var total = mergeTwoLists(l1,l2)
    console.log(total) // ok