<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) {
        const int sum = accumulate(nums.begin(),nums.end(),0);
        if(sum % 2 != 0)
            return false;
        const int tgt = sum/2;
        unordered_set<int> s;
        s.insert(0);
        for(const auto v:nums) {
            // if(v == tgt)
            //     return true;
            unordered_set<int> cur;
            for(const auto sum:s) {
                if(v + sum == tgt)
                    return true;
                cur.insert(sum + v);
            }
            s.insert(cur.begin(),cur.end());
        }
        return false;
    }
};
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