<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:
    int val;
    vector<int> dp;
    bool solve(vector<int> &nums, int k, int curr, int mask, int i){
        if(k == 1) return true;
        if(i >= nums.size()) return false;

        if(dp[mask] != -1) return dp[mask];

        if(curr == val) return dp[mask] = solve(nums, k-1, 0, mask, 0);

        for(int j = i; j<nums.size(); j++){
            if(!(mask&(1<<j)) && curr+nums[j] <= val && solve(nums, k, curr+nums[j], mask|(1<<j), j+1)) return dp[mask] = true;
        }
        return dp[mask] = false;
    }

    bool canPartitionKSubsets(vector<int>& nums, int k) {
        int sum = accumulate(nums.begin(), nums.end(), 0);
        if(sum%k) return false;
        val = sum/k;
        dp.resize(1<<(nums.size()+1), -1);
        return solve(nums, k, 0, 0, 0);
    }
};
34664