15_3sum.py

class Solution:
    def threeSum(self, nums: List[int]) -> List[List[int]]:
        if len(nums) < 3:
            return []
        nums.sort()
        ans = []
        for i in range(len(nums)-2):
            # Some details
            if (i >= 1) and (nums[i] == nums[i-1]):
                continue
            if nums[i] > 0:
                break
            left = i+1
            right = len(nums) - 1
            while left < right:
                tmp_sum = nums[i] + nums[left] + nums[right]
                if tmp_sum < 0:
                    left += 1
                elif tmp_sum > 0:
                    right -= 1
                else:
                    ans.append([nums[i], nums[left], nums[right]])
                    while (left < right) and (nums[left+1] == nums[left]):
                        left += 1
                    while (left < right) and (nums[right-1] == nums[right]):
                        right -= 1
                    left += 1
                    right -= 1
        return ans

'''
    This is my personal record of solving Leetcode Problems. 
    If you have any questions, please discuss them in [Issues](https://github.com/mengxinayan/leetcode/issues).
    Copyright (C) 2020-2022  mengxinayan

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
'''