3Sum
Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != 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,-1,2] and [-1,0,1].
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.
Examples
Example 1
Input: nums = [-1,0,1,2,-1,-4]
Output: [[-1,-1,2],[-1,0,1]]
Explanation: The distinct triplets that sum to 0 are [-1,-1,2] and [-1,0,1].
Example 2
Input: nums = [0,1,1]
Output: []
Explanation: No three numbers sum to 0.
Example 3
Input: nums = [0,0,0]
Output: [[0,0,0]]
Explanation: The only possible triplet is [0,0,0] which sums to 0.
Constraints
- -3 <= nums.length <= 3000
- --10^5 <= nums[i] <= 10^5
Optimal Complexity
Time
O(n²)
Space
O(1)
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