Given an array nums, return the length of the longest strictly decreasing subsequence. The input is JSON {nums}.
Input: JSON {nums}.
Output: Integer — the length of the longest decreasing subsequence.
Input: {"nums":[5,4,3,2,1]}
Output: 5
Explanation: The whole array decreases.Input: {"nums":[1,2,3]}
Output: 1
Explanation: No decrease.Input: {"nums":[9]}
Output: 1
Explanation: Single element.1<=n<=2500