Given an integer array nums, return all the different possible non-decreasing subsequences of the given array with at least two elements. You may return the answer in any order.
A subsequence is a sequence that can be derived from the array by deleting some or no elements without changing the order of the remaining elements.
Example 1:
Input: nums = [4,6,7,7]
Output: [[4,6],[4,6,7],[4,6,7,7],[4,7],[4,7,7],[6,7],[6,7,7],[7,7]]
Explanation: All non-decreasing subsequences with at least 2 elements are listed.
Example 2:
Input: nums = [4,4,3,2,1]
Output: [[4,4]]
Explanation: The only non-decreasing subsequence with at least 2 elements is [4,4].
Example 3:
Input: nums = [1,2,3]
Output: [[1,2],[1,2,3],[1,3],[2,3]]
Explanation: All possible non-decreasing subsequences with at least 2 elements.
1 <= nums.length <= 15-100 <= nums[i] <= 100