<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 totalSum = 0;
    
    // Calculate total sum of the array
    for (int num : nums) {
        totalSum += num;
    }
    
    // If the total sum is odd, we cannot partition into two equal subsets
    if (totalSum % 2 != 0) {
        return false;
    }
    
    // Target sum for each subset
    int target = totalSum / 2;
    
    // Hash map to store possible sums
    unordered_map<int, bool> hashMap;
    hashMap[0] = true;  // Sum 0 is always possible (empty subset)
    
    // Iterate over each element in the array
    for (int num : nums) {
        unordered_map<int, bool> newSums = hashMap;
        
        // Check all sums already in the map
        for (auto pair : hashMap) {
            int currentSum = pair.first;
            
            // Calculate new sum by adding the current element
            int newSum = currentSum + num;
            
            // If the new sum equals the target, we found a valid partition
            if (newSum == target) {
                return true;
            }
            
            // Add the new sum to the temporary hash map
            newSums[newSum] = true;
        }
        
        // Update the hash map with the new sums
        hashMap = newSums;
    }
    
    // If we finished the loop without finding the target sum, return false
    return false;
    }
};
199675