题解 | #三数之和#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param num int整型一维数组 
# @return int整型二维数组
#
from typing import List

class Solution:
    def threeSum(self , num: List[int]) -> List[List[int]]:
        # write code here
        n = len(num)
        num.sort()
        ans = []
        for i in range(n - 2):
            x = num[i]
            if i > 0 and x == num[i - 1]:
                continue
            if x + num[i + 1] + num[i + 2] > 0:
                break
            if x + num[-2] + num[-1] < 0:
                continue
            j, k = i + 1, n - 1
            while j < k:
                s = x + num[j] + num[k]
                if s > 0:
                    k -= 1
                elif s < 0:
                    j += 1
                else:
                    ans.append([x, num[j], num[k]])
                    j += 1
                    while j < k and num[j] == num[j - 1]:
                        j += 1
                    k -= 1
                    while j < k and num[k] == num[k + 1]:
                        k -= 1
        return ans