3Sum
Explore how to identify all unique triplets in an array that sum to zero by mastering the two pointers technique. Understand how to avoid duplicates and apply this strategy to similar coding problems, enhancing your problem-solving skills for coding interviews.
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Statement
Given an integer array nums, find all unique triplets [nums[i], nums[j], nums[k]] where i, j, and k are distinct indices, such that the three elements sum to zero.
The result must not contain any duplicate triplets. The order of the output and the order of elements within each triplet does not matter.
Note: The solution set must only include unique triplets. Two triplets are considered duplicates if they contain the same elements regardless of ordering.
Constraints:
nums.lengthnums[i]
Examples
Understand the problem
Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:
3Sum
Given nums = [-3, -3, 6, 1, 2, -3], how many unique triplets sum to zero?
3
2
1
0
Figure it out!
We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.
Try it yourself
Implement your solution in the following coding playground.
Need a nudge?
Explore these hints—each one is designed to guide you a step closer to the solution.
import java.util.*;public class Solution {public static List<List<Integer>> threeSum(int[] nums) {// Replace this placeholder return statement with your codereturn new ArrayList<>();}}