<p>You are given an array <code>nums</code> of positive integers and a <strong>positive</strong> integer <code>k</code>.</p>

<p>A subset of <code>nums</code> is <strong>beautiful</strong> if it does not contain two integers with an absolute difference equal to <code>k</code>.</p>

<p>Return <em>the number of <strong>non-empty beautiful </strong>subsets of the array</em> <code>nums</code>.</p>

<p>A <strong>subset</strong> of <code>nums</code> is an array that can be obtained by deleting some (possibly none) elements from <code>nums</code>. Two subsets are different if and only if the chosen indices to delete are different.</p>

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

<pre>
<strong>Input:</strong> nums = [2,4,6], k = 2
<strong>Output:</strong> 4
<strong>Explanation:</strong> The beautiful subsets of the array nums are: [2], [4], [6], [2, 6].
It can be proved that there are only 4 beautiful subsets in the array [2,4,6].
</pre>

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

<pre>
<strong>Input:</strong> nums = [1], k = 1
<strong>Output:</strong> 1
<strong>Explanation:</strong> The beautiful subset of the array nums is [1].
It can be proved that there is only 1 beautiful subset in the array [1].
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 20</code></li>
	<li><code>1 &lt;= nums[i], k &lt;= 1000</code></li>
</ul>

class Solution {
public:
    int res = 0;
    int beautifulSubsets(vector<int>& nums, int k) {
        unordered_multiset<int> valueMap;
        recuSubset(nums, k, valueMap, 0);
        return res;
    }

    void recuSubset(vector<int> nums, int k, unordered_multiset<int> &valueMap, int index) {
        if(index == nums.size()) return;
        for(int i=index;i<nums.size();i++) {
            int val = nums[i];
            if(valueMap.find(val+k) == valueMap.end() && valueMap.find(val-k) == valueMap.end()) {
                res += 1;//(valueSet.size() == 0 ? 1 : valueSet.size());
                valueMap.insert(val);
                recuSubset(nums,k,valueMap,i+1);
                valueMap.erase(valueMap.find(val));
            }
        }
    }
};
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