3sum

Given an array nums of n integers, are there elements a, b, c in nums such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.

Note:

The solution set must not contain duplicate triplets.

Example:

Given array nums = [-1, 0, 1, 2, -1, -4],

A solution set is:
[
  [-1, 0, 1],
  [-1, -1, 2]
]

My code:
import numpy as np
class Solution:
    def threeSum(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        result=[]
        index=np.argsort(nums)
        
        for i in range(len(nums)-2):
            if i>=1:
                if nums[index[i]]==nums[index[i-1]]:
                    continue
            require=-nums[index[i]]
            #print(-require)
            lstart=i+1
            rstart=len(nums)-1
            while lstart<rstart:
                number1=nums[index[lstart]]
                number2=nums[index[rstart]]
                #print('lstart %d value %d'%(lstart,number1))
                if number1+number2==require:
                    result.append([-require,number1,number2])
                    while nums[index[lstart+1]]==nums[index[lstart]] and lstart+1<rstart:
                        lstart+=1
                    while nums[index[rstart-1]]==nums[index[rstart]] and rstart-1>lstart:
                        rstart-=1
                    lstart+=1
                    rstart-=1
                elif number1+number2>require:
                    rstart-=1
                else:
                    lstart+=1
        return result
                    
  #This is a o(n^2) operation, but python version can't pass the leetcode testing. I can say there will be no better algorithms better than this.So do not worry about time problem.
  Solution:
  https://leetcode.com/problems/3sum/