3Sum LeetCode solution in Python

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class Solution(object):
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    def threeSum(self, nums):
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        ans = []
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        nums.sort()
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        for i in range(len(nums)):
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            if nums[i] > 0:
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                break  # after sorting, if the min > 0, we couldn't find such three values
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            if (
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                i > 0 and nums[i] == nums[i - 1]
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            ):  # ensure that nums[i] is not duplicated
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                continue
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            l, r = i + 1, len(nums) - 1
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            while l < r:
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                if nums[l] + nums[r] > -nums[i]:
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                    r -= 1
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                elif nums[l] + nums[r] < -nums[i]:
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                    l += 1
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                else:
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                    ans.append([nums[i], nums[l], nums[r]])
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                    # update l to get a different sum
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                    l += 1
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                    while nums[l] == nums[l - 1] and l < r:
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                        l += 1
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        return ans