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15.三数之和.py
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15.三数之和.py
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#
# @lc app=leetcode.cn id=15 lang=python3
#
# [15] 三数之和
#
# @lc code=start
from typing import List
import bisect
class Solution:
def __init__(self):
self.res = []
def threeSum(self, nums: List[int]) -> List[List[int]]:
if not nums or len(nums) < 3:return []
nums.sort()
for k, v in enumerate(nums):
if v > 0:
return self.res
if k > 0 and v == nums[k-1]:
continue
L, R = k+1,len(nums)-1
while L < R:
_sum = v + nums[L]+nums[R]
# 定义双指针,L,R指向的数和数V进行加和,判断大小并决定L,R指针向哪边移动
if _sum == 0:
self.res.append([v, nums[L], nums[R]])
# 当遇到L,R让三个数字和为0,如果L,R临近的点是重复的就先移动的重复的那个指针,如果没有就一起移动L,R,若不一起移动,单移动一边无法创造三个数和为0
L = bisect.bisect_right(nums,nums[L], L, R)
R = bisect.bisect_left(nums,nums[R], L, R)-1
else:
L,R = L+(_sum < 0),R-(_sum > 0)
return self.res
# @lc code=end
if __name__ == "__main__":
test = Solution()
print(test.threeSum([1,-1,-1,0]))