题解 | #三数之和#

采用双指针的方法，并进行排序保证没有重复

class Solution:
    def threeSum(self , num: List[int]) -> List[List[int]]:
        # write code here
        n=len(num)
        res=[]
        num.sort()
        for first in range(n):
            if first >0 and num[first]==num[first-1]:
                continue
            third=n-1
            target=-num[first]
            for second in range(first+1,n):
                if second>first+1 and num[second]==num[second-1]:
                    continue
                while second<third and num[second]+num[third]>target:
                    third-=1
                if second==third:
                    break
                if num[second]+num[third]==target:
                    res.append([num[first],num[second],num[third]])
        return res