problem18

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18. 4Sum (Medium)

Given an array nums of n integers and an integer target, are there elements a, b, c, and d in nums such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.

Notice that the solution set must not contain duplicate quadruplets.

Example 1:

Input: nums = [1,0,-1,0,-2,2], target = 0
Output: [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]

Example 2:

Input: nums = [], target = 0
Output: []

Constraints:

• 0 <= nums.length <= 200
• -109 <= nums[i] <= 109
• -109 <= target <= 109

Related Topics

[Array] [Hash Table] [Two Pointers]

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