# -*- coding: UTF-8 -*-

class Solution:
    def fourSum(self, nums, target):
        if len(nums) <= 3:
            return []
        nums = sorted(nums)
        rtn = []
        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
                left, right = j+1, len(nums)-1
                while left < right:
                    total = nums[i]+nums[j]+nums[left]+nums[right]
                    if total < target:
                        left += 1
                    elif total > target:
                        right -= 1
                    else:
                        rtn.append([nums[i],nums[j],nums[left],nums[right]])
                        while left<right and nums[left]==nums[left+1]:
                            left += 1
                        while left<right and nums[right]==nums[right-1]:
                            right -= 1
                        left += 1
                        right -= 1
        return rtn