<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 isSubsetSum(vector<int>arr, int sum){
        int n = arr.size();
        vector<vector<int>> dp(n+1 , vector<int> (sum+1 , 0)); 
        vector<int> curr (sum+1 , 0);
        vector<int>prev (sum+1 , 0);
        
        if (arr[0] <= sum){
            prev[arr[0]] = 1;
        }
        for (int i = 0 ; i < n ; i++){
            prev[0] = 1;
        }
        
        for (int i = 1 ; i < n ; i++){
            for (int j = 0 ; j <= sum ; j++){
                bool a = false;
                if (j-arr[i] < 0){
                    a = false;
                }
                else{
                    a =prev[j-arr[i]];
                }
                //not take 
                bool b = prev[j];
               
               curr[j] = a||b;
            }
            prev = curr;
           // prev[0] = 1;
        }
        return curr[sum];
    }

    bool canPartition(vector<int>& nums) {
        int sum = 0 ;
        for (int i = 0 ; i < nums.size() ; i++){
            sum += nums[i];
        }
        if(sum %2 == 1){
            return false;
        }
        else{
            return isSubsetSum( nums , sum/2);
        }
    }
};
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