vllbc02三数之和
三数之和
题目：
https://leetcode-cn.com/problems/3sum/solution/
思路：
第一眼看就想到了用双指针，注意重复数值的处理问题，算是一个滑动窗口问题
代码：
class Solution:
def threeSum(self, nums: List[int]) -> List[List[int]]:
res = []
if len(nums) < 3:
return []
nums.sort()
for i, num in enumerate(nums):
if num > 0:
return res
if i > 0 and nums[i] == nums[i-1]:
continue
left, right = i+1, len(nums) - 1
while left < right:
temp = nums[i] + nums[left] + nums[right]
if temp == 0:
res.append([nums[i], nums[left], nums[right]])
while left < right and nums[right-1] == nums[right]:
right -= 1
while left < right and nums[left+1] == nums[left]:
left += 1
left += 1
right -= 1
if temp > 0:
right -=1
if temp < 0:
left += 1
return res