'''

Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:

0 <= a, b, c, d < n

a, b, c, and d are distinct.

nums[a] + nums[b] + nums[c] + nums[d] == target

You may return the answer in any order.

Example 1:

Input: nums = [1,0,-1,0,-2,2], target = 0

Output: [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]

Example 2:

Input: nums = [2,2,2,2,2], target = 8

Output: [[2,2,2,2]]

Constraints:

1 <= nums.length <= 200

-109 <= nums[i] <= 109

-109 <= target <= 109

'''

class Solution:

def fourSum(self, nums: List[int], target: int) -> List[List[int]]:

nums.sort()

res = []

for i in range(len(nums)-3):

if i > 0 and nums[i] == nums[i-1]:

continue

for j in range(i+1, len(nums)-2):

if j > i+1 and nums[j] == nums[j-1]:

continue

l, r = j+1, len(nums)-1

while l < r:

s = nums[i] + nums[j] + nums[l] + nums[r]

if s == target:

res.append([nums[i], nums[j], nums[l], nums[r]])

l += 1

r -= 1

while l < r and nums[l] == nums[l-1]:

l += 1

while l < r and nums[r] == nums[r+1]:

r -= 1

elif s < target:

l += 1

else:

r -= 1

return res