3sum.py

def threeSum(nums):
    # Sort the input array
    nums.sort()
    result = []

    for i in range(len(nums) - 2):
        # Skip duplicates to avoid duplicate triplets
        if i > 0 and nums[i] == nums[i - 1]:
            continue

        left, right = i + 1, len(nums) - 1

        while left < right:
            total = nums[i] + nums[left] + nums[right]

            if total == 0:
                result.append([nums[i], nums[left], nums[right]])
                # Skip duplicates
                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 < 0:
                left += 1
            else:
                right -= 1

    return result