Leetcode 15. 3Sum（python）

先排序，再循环遍历，用双指针。

class Solution(object):
    def threeSum(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        solution=[]
        nums.sort()
        for i in range(len(nums)-1):
            left=i+1
            right=len(nums)-1
            while left<right:
                val=nums[i]+nums[left]+nums[right]
                if val==0 and [nums[i],nums[left],nums[right]] not in solution:
                    solution.append([nums[i],nums[left],nums[right]])
                    left+=1
                    right-=1
                elif val<0:
                    left+=1
                else:
                    right-=1
        return solution