<p>Given an integer array <code>nums</code>, return <code>true</code> <em>if you can partition the array into two subsets such that the sum of the elements in both subsets is equal or </em><code>false</code><em> otherwise</em>.</p>

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

<pre>
<strong>Input:</strong> nums = [1,5,11,5]
<strong>Output:</strong> true
<strong>Explanation:</strong> The array can be partitioned as [1, 5, 5] and [11].
</pre>

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

<pre>
<strong>Input:</strong> nums = [1,2,3,5]
<strong>Output:</strong> false
<strong>Explanation:</strong> The array cannot be partitioned into equal sum subsets.
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 100</code></li>
</ul>

class Solution {
public:
    
    bool canPartition(vector<int>& nums) {
        
        int n = nums.size();
        
        int ac = accumulate(nums.begin(), nums.end(), 0);
        if(ac % 2) return false;
        int hf = ac/2;
        
        unordered_set<int> s, s1;
        for(int i=0; i<n; i++)
        {
            if(nums[i] == hf) return true;
            for(int j: s)
            {
                if(j + nums[i] < hf) s1.insert(j+nums[i]);
                else if (j + nums[i] == hf) return true;
            }
            
            s1.insert(nums[i]);
            s.insert(s1.begin(), s1.end()), s1.clear();
        }
        return false;
    }
};
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