<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 {
public:
    vector<vector<int>> findSubsequences(vector<int>& nums) {
        vector<vector<int>> res;
        stack<pair<int, vector<int>>> st;
        st.push({0, {}});

        while (!st.empty()) {
            auto [i, curr] = st.top();
            st.pop();

            if (i == nums.size()) {
                if (curr.size() >= 2) {
                    res.push_back(curr);
                }
                continue;
            }

            // Simulate the "not choose" part
            st.push({i + 1, curr});

            // Simulate the "choose" part
            if (curr.empty() || nums[i] >= curr.back()) {
                curr.push_back(nums[i]);
                st.push({i + 1, curr});
            }
        }

        // Remove duplicates
        set<vector<int>> uniqueRes(res.begin(), res.end());
        res.assign(uniqueRes.begin(), uniqueRes.end());

        return res;
    }
};

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