<p>Given an array <code>nums</code> of <code>n</code> integers, return <em>an array of all the <strong>unique</strong> quadruplets</em> <code>[nums[a], nums[b], nums[c], nums[d]]</code> such that:</p>

<ul>
	<li><code>0 &lt;= a, b, c, d&nbsp;&lt; n</code></li>
	<li><code>a</code>, <code>b</code>, <code>c</code>, and <code>d</code> are <strong>distinct</strong>.</li>
	<li><code>nums[a] + nums[b] + nums[c] + nums[d] == target</code></li>
</ul>

<p>You may return the answer in <strong>any order</strong>.</p>

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

<pre>
<strong>Input:</strong> nums = [1,0,-1,0,-2,2], target = 0
<strong>Output:</strong> [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
</pre>

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

<pre>
<strong>Input:</strong> nums = [2,2,2,2,2], target = 8
<strong>Output:</strong> [[2,2,2,2]]
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
	<li><code>-10<sup>9</sup> &lt;= target &lt;= 10<sup>9</sup></code></li>
</ul>

class Solution:
    def fourSum(self, nums: List[int], target: int) -> List[List[int]]:
        nums.sort()  # Sort the array first
        n = len(nums)
        result = []
        
        for a in range(n - 3):
            # Skip duplicates for a
            if a > 0 and nums[a] == nums[a-1]:
                continue
            
            for b in range(a + 1, n - 2):
                # Skip duplicates for b
                if b > a + 1 and nums[b] == nums[b-1]:
                    continue
                
                c = b + 1
                d = n - 1
                
                while c < d:
                    current_sum = nums[a] + nums[b] + nums[c] + nums[d]
                    
                    if current_sum == target:
                        result.append([nums[a], nums[b], nums[c], nums[d]])
                        
                        # Skip duplicates for c and d
                        while c < d and nums[c] == nums[c+1]:
                            c += 1
                        while c < d and nums[d] == nums[d-1]:
                            d -= 1
                        
                        c += 1
                        d -= 1
                    elif current_sum < target:
                        c += 1
                    else:
                        d -= 1
        
        return result
16100