[LeetCode] 0015. 3Sum

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Medium

 


Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != ji != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.

Notice that the solution set must not contain duplicate triplets.

Example 1:

Input: nums = [-1,0,1,2,-1,-4]
Output: [[-1,-1,2],[-1,0,1]]
Explanation: 
nums[0] + nums[1] + nums[2] = (-1) + 0 + 1 = 0. nums[1] + nums[2] + nums[4] = 0 + 1 + (-1) = 0. nums[0] + nums[3] + nums[4] = (-1) + 2 + (-1) = 0. The distinct triplets are [-1,0,1] and [-1,-1 ,2]. Notice that the order of the output and the order of the triplets does not matter.

Example 2:

Input: nums = [0,1,1]
Output: []
Explanation: The only possible triplet does not sum up to 0.

Example 3:

Input: nums = [0,0,0]
Output: [[0,0,0]]
Explanation: The only possible triplet sums up to 0.

Constraints:

  • 3 <= nums.length <= 3000
  • -10 5 <= nums[i] <= 10 5

Python

				
					class Solution: def twoSum(self, nums: List[int], i: int, result: List[List[int]]): low = i + 1 hight = len(nums) - 1 while (low < hight): sum = nums[i] + nums[low] + nums[hight] if sum < 0: low += 1 elif sum > 0: hight -= 1 else: result.append([nums[i], nums[low] , nums[hight]]) low += 1 hight -= 1 while low < hight and nums[low] == nums[low - 1]: low += 1 def threeSum(self, nums: List[int]) - > List[List[int]]: result = [] nums.sort() for i, item in enumerate(nums): if item > 0: break if item != nums[i-1] or i == 0: self.twoSum(nums, i, result) return result
				
			
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