leetcode/3Sum15.py at main · ahritik/leetcode · GitHub

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"""
15. 3Sum

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such
that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.
Notice that the solution set must not contain duplicate triplets.
"""

def threeSum(nums):
    nums.sort()
    triplets = []

    for i in range(len(nums) - 2):
        if i > 0 and nums[i] == nums[i - 1]:
            continue
        left, right = i + 1, len(nums) - 1

        while left < right:
            s = nums[i] + nums[left] + nums[right]
            if s < 0:
                left += 1
            elif s > 0:
                right -= 1
            else:
                triplets.append([nums[i], 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 triplets