3Sum.py

#! /usr/bin/env python3
# -*- coding: utf-8 -*-

# Source: https://leetcode.com/problems/3sum/
# Author: Miao Zhang
# Date:   2021-01-05

class Solution:
    def threeSum(self, nums: List[int]) -> List[List[int]]:
        nums.sort()
        n = len(nums)
        res = []
        for i in range(n - 2):
            if i > 0 and nums[i] == nums[i - 1]:
                continue
            target = -1 * nums[i]
            j, k = i + 1, n - 1
            while j < k:
                if nums[j] + nums[k] == target:
                    res.append([nums[i], nums[j], nums[k]])
                    j += 1
                    while j < k and nums[j - 1] == nums[j]:
                        j += 1
                elif nums[j] + nums[k] > target:
                    k -= 1
                else:
                    j += 1
        return res