<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <code>true</code> if it is possible to divide this array into <code>k</code> non-empty subsets whose sums are all equal.</p>

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

<pre>
<strong>Input:</strong> nums = [4,3,2,3,5,2,1], k = 4
<strong>Output:</strong> true
<strong>Explanation:</strong> It is possible to divide it into 4 subsets (5), (1, 4), (2,3), (2,3) with equal sums.
</pre>

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

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

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

<ul>
	<li><code>1 &lt;= k &lt;= nums.length &lt;= 16</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
	<li>The frequency of each element is in the range <code>[1, 4]</code>.</li>
</ul>

class Solution {
public:
    bool help(int ind, int k, int sum, int target, vector<int>&nums, vector<bool>&used)
    {
        if(k==0)
        {
            return true;
        }
        if(sum==target)
        {
            return help(0, k-1, 0, target, nums, used);
        }
        for(int i=ind;i<nums.size();i++)
        {
            if(used[i]==true||sum+nums[i]>target)
            {
                continue;
            }
            else
            {
                used[i]=true;
                if(help(i+1, k, sum+nums[i], target, nums, used)==true)
                {
                    return true;
                }
                used[i]=false;
                if(sum==0)
                {
                    break;
                }
            }
        }
        return false;
    }
    bool canPartitionKSubsets(vector<int>& nums, int k) 
    {
        int target=0;
        sort(nums.begin(), nums.end());
        vector<bool>used(nums.size(), false);
        for(int i=0;i<nums.size();i++)
        {
            target+=nums[i];
        }
        if(target%k!=0)
        {
            return false;
        }
        return help(0, k, 0, target/k, nums, used);
    }
};
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