<p>Given an integer array <code>nums</code>, return <em>all the different possible non-decreasing subsequences of the given array with at least two elements</em>. You may return the answer in <strong>any order</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [4,6,7,7]
<strong>Output:</strong> [[4,6],[4,6,7],[4,6,7,7],[4,7],[4,7,7],[6,7],[6,7,7],[7,7]]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [4,4,3,2,1]
<strong>Output:</strong> [[4,4]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 15</code></li>
	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
</ul>

class Solution {
private: 
    void solve(int index, int mask, vector<int>& v, vector<int>& nums, vector<vector<int>>& ans, vector<int>& dp){
        if(index==nums.size()){
            if(!dp[mask] && v.size()>1){
                ans.push_back(v);
                dp[mask]=1;
            }

            return;
        }

        int sz=v.size();
        if(!sz){
            v.push_back(nums[index]);
            solve(index+1,(1<<index),v,nums,ans,dp);
            v.pop_back();
            solve(index+1,0,v,nums,ans,dp);
        }
        else{
            if(nums[index]>=v[sz-1]){
                v.push_back(nums[index]);
                solve(index+1,mask|(1<<index),v,nums,ans,dp);
                v.pop_back();
            }
            solve(index+1,mask,v,nums,ans,dp);
        }

        return;
    }
public:
    vector<vector<int>> findSubsequences(vector<int>& nums) {
        int n=nums.size();
        vector<int> dp((1<<(n+1)),0);
        vector<vector<int>> ans;
        vector<int> v;
        solve(0,0,v,nums,ans,dp);

        set<vector<int>> st;
        for(auto it : ans){
            st.insert(it);
        }

        ans.clear();
        for(auto it : st){
            ans.push_back(it);
        }
        return ans;
    }
};
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