leetcode-algorithms/src/ThreeSum.java at master · anishLearnsToCode/leetcode-algorithms · GitHub

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import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

public class ThreeSum {

public List<List<Integer>> threeSum(int[] nums) {

if (nums.length < 3) return Collections.emptyList();

final Set<List<Integer>> triplets = new HashSet<>();

Arrays.sort(nums);

for (int i = 0; i < nums.length - 2; i++) {

for (int j = i + 1, k = nums.length - 1 ; j < k ; ) {

int sum = nums[i] + nums[j] + nums[k];

if (sum == 0) triplets.add(List.of(nums[i], nums[j++], nums[k--]));

else if (sum > 0) k--;

else j++;

}

return new ArrayList<>(triplets);

}

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