Leetcode 18. 4Sum

Question:

Answer:

    def fourSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[List[int]]
        """
        if not nums and len(nums) < 4:
            return []
        
        nums.sort()
        result = []
        
        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 = j + 1
                right = len(nums) - 1
                remaining = target - nums[i] - nums[j]
                while left < right:
                    total = nums[left] + nums[right]
                    if total == remaining:
                        result.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
                    elif total < remaining:
                        left += 1
                    else:
                        right -= 1
        return result