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21. Merge Two Sorted Lists
Easy
Merge two sorted linked lists and return it as a sorted list. The list should be made by splicing together the nodes of the first two lists.
Example 1:
Input: l1 = [1,2,4], l2 = [1,3,4]
Output: [1,1,2,3,4,4]
Example 2:
Input: l1 = [], l2 = []
Output: []
Example 3:
Input: l1 = [], l2 = [0]
Output: [0]
Constraints:
- The number of nodes in both lists is in the range
[0, 50]. -100 <= Node.val <= 100- Both
l1andl2are sorted in non-decreasing order.
Solution
# Definition for singly-linked list.
# class ListNode
# attr_accessor :val, :next
# def initialize(val = 0, _next = nil)
# @val = val
# @next = _next
# end
# end
# @param {ListNode} list1
# @param {ListNode} list2
# @return {ListNode}
def merge_two_lists(list1, list2)
list = ListNode.new(-1)
head = list
while list1 || list2
if list1 && list2
if list1.val <= list2.val
list.next = ListNode.new(list1.val)
list1 = list1.next
else
list.next = ListNode.new(list2.val)
list2 = list2.next
end
elsif list1
list.next = ListNode.new(list1.val)
list1 = list1.next
else
list.next = ListNode.new(list2.val)
list2 = list2.next
end
list = list.next
end
head.next
end