3Sum

/*
Logic:one loop on whole array for one elemnt of triplet and other two element will be found by two-pointer.
*/

class Solution:
    def threeSum(self, nums: List[int]) -> List[List[int]]:
        nums.sort()
        ans=[]
        for i in range(len(nums)):
            if i>0 and nums[i]==nums[i-1]:
                continue
            j=i+1
            k=len(nums)-1
            while j<k:
                if nums[i]+nums[j]+nums[k]==0:
                    ans.append([nums[i],nums[j],nums[k]])
                    j+=1
                    k-=1
                    while j<k and nums[j]==nums[j-1]: #These two while is there if suppose 1M 0 is there in array
                        j+=1
                    while k>j and nums[k]==nums[k+1]:
                        k-=1
                elif nums[i]+nums[j]+nums[k]>0:
                    k-=1
                else:
                    j+=1
        return ans