Find all triplets with zero sum without duplicates. This is the 3Sum problem on LeetCode.
Find all triplets with zero sum without duplicates. In other words, given an array arr and a target value target, return all triplets a, b, c such that a + b + c = target. This method ensures that we efficiently explore potential triplets while avoiding duplicates. If the sum is greater than zero, move the right pointer to the left to decrease the sum. So I don't think you can do better than quadratic. Note: The solution set must not contain duplicate triplets. Jul 2, 2025 · If the sum is less than zero, move the left pointer to the right to increase the sum. Follow our step-by-step guide with examples. Nov 10, 2024 · What is 3Sum? The 3Sum problem asks us to find all unique triplets in an array that sum up to zero. Since there can be multiple valid pairs, we add each one to the hash set (to manage duplicates) while ensuring that all indices in the triplet are distinct. Oct 20, 2024 · Then, for each element in the array, we check if the pair which makes triplet's sum zero, exists in the hash map or not. Feb 28, 2015 · Disregarding the "unique" requirement, the number of triplets that can sum to zero is quadratic in the length of the array. We can return triplets in any order, but all the returned triplets should be internally sorted, i. Specifically, you need to find all the triplets ` [nums [i], nums [j], nums [k]]` such that `i != j`, `i != k`, `j != k`, and the sum of `nums [i] + nums [j] + nums [k] == 0`. com Oct 6, 2018 · Got this in an interview. Imagine you’re building a balance scale app, and you need to find three weights that perfectly balance each other. Sounds simple, right? Well, the devil’s in the details! Let’s break it down with a real-world analogy. It avoids duplicates by skipping over repeated elements. Oct 6, 2024 · Given an array nums of n integers, the task is to find all unique triplets (i. Jan 2, 2025 · The task is to find all unique triplets in an array that add up to zero. The threeSum method first sorts the array and then iterates through it, using two pointers for each element to find the other two elements that sum up to zero. For each combination of three elements, we first check if their sum equals zero, and then we sort the triplet and use a set to ensure we only include unique combinations. Exercise in Python: Given the following problem and solution, write a test program, with test cases that you come up with on your own to verify the solution. Aug 12, 2016 · Find all unique triplets in the array which gives the sum of zero. Jul 23, 2025 · Your All-in-One Learning Portal: GeeksforGeeks is a comprehensive educational platform that empowers learners across domains-spanning computer science and programming, school education, upskilling, commerce, software tools, competitive exams, and more. **Example 1**: ``` Input: nums = [-1 Discover all unique triplets that sum to zero using two-pointer approach with interactive coding challenge. The question is very similar to the very famous question Find a triplet that sum to a given value, with a slight difference. Count Pairs whose sum is less than target Count Smaller elements Count Subarrays with given XOR Count all triplets with given sum in sorted array Count distinct elements in every window Count numbers containing 4 Count pairs Sum in matrices Given an array of integers nums, find all unique triplets in nums that sum up to zero, where all elements in a triplet are different elements from the array. For the input array [-1, 0, 1, 2, -1, -4], the method finds two unique triplets that sum up to zero: [-1, -1, 2] and [-1, 0, 1]. Example 2: Input: nums = [0,1,1] Output: [] Explanation: The only possible triplet does not sum up to 0. See full list on enjoyalgorithms. This step-by-step guide explains time complexity, duplicate handling, and optimization techniques for finding unique triplets that sum to zero in an array. Examples: Feb 14, 2025 · [Naive Approach] Using Three Nested Loops - O (n^3) Time and O (n^2) Space The idea is to generate all possible triplets in the array using three nested loops, then store each unique valid triplet in a result vector. Aug 13, 2025 · 3 Sum – Find all Triplets with Given Sum 3 Sum – Triplet Sum Closest to Target 3 Sum – Pythagorean Triplet in an array 3 Sum – All Distinct Triplets with given Sum Pythagorean Triplet with given sum Count triplets with sum smaller than a given value Please refer 3Sum - Complete Tutorial for all list of problems on triplets in an array. 🚀 Day 44 🌟 GfG 160 - 160 Days of Problem Solving! 🎯 Problem: Find All Triplets with Zero Sum 🔍 Problem Statement: Given an array arr [] of integers, the task is to find all unique Aug 25, 2020 · Find all unique triplets in the array which gives the sum of zero Asked 4 years, 11 months ago Modified 4 years, 5 months ago Viewed 1k times May 24, 2025 · Python Exercises, Practice and Solution: Write a Python program to identify unique triplets whose three elements sum to zero from an array of n integers. We iterate through all pairs (j, k), compute the required third element as -(arr[j] + arr[k]), and check if it exists in the map with a valid index i < j. Notice that the solution set must not contain duplicate triplets. A significant part of avoiding duplicates involves, after finding a valid triplet, skipping all other i values which are the same as nums[i]. Nov 14, 2024 · Learn how to solve the 3 Sum problem by finding all distinct triplets that add up to a given sum. Jul 23, 2025 · The idea is to use a hash map to store indices of each element and efficiently find triplets that sum to zero. Here You will find the code for Geeks For Geeks Problem of the Day - Data-Structure/Find triplets with zero sum at main · ShubhamKashyap138/Data-Structure Find all unique triplets in the array which gives the sum of zero. , for any triplet [q1, q2, q3], the condition q1 ≤ q2 ≤ q3 should hold. Jan 8, 2025 · Given an array arr [], and an integer target, find all possible unique triplets in the array whose sum is equal to the given target value. The solution set must not contain duplicate triplets. Skip Duplicates: After finding a triplet or moving a pointer, always skip the duplicate numbers to avoid duplicate triplets in the result. Given an array of unsorted numbers, find all **unique** triplets in the array whose sum is zero. Given an array of integers `nums`, your task is to find all unique triplets in the array which give the sum of zero. To avoid duplicates I use an if-clause in the while loop, and I was wondering why this does not work. If found, we store {i, j, k} in the result. Notice that the order of the output and the order of the triplets does not matter. This is the 3Sum problem on LeetCode. For example, given array S = [-1, 0, 1, 2, -1, -4] A solution set is: [ [-1, 0, 1], [-1, -1, 2] ] Below is my algorithm that works reasonably and as expected, but I'm unable to figure out how to prevent duplicates. Dec 9, 2024 · Learn how to solve LeetCode's 3Sum problem efficiently using the Two-Pointer and Dictionary-Based approaches. However, it's trivial to do quadratic. However, the time complexity of this solution is O (n^3) as we have to run 3 nested loops in order to implement this. . Example: Jan 24, 2016 · Find all unique triplets in the array which gives the sum of zero. Here we want to print ALL triplets, not just o To find all unique triplets in an array that sum to zero, we can utilize a combination of sorting and a two-pointer approach. In brute force approach we find every possible triplet from the given array, check if its sum is equal to zero and return the result (ensuring there are no duplicate triplets in the result). , three numbers) in the array which sum to zero. The array may have duplicates. Apr 15, 2024 · Check for Zero Sum: If the sum of the numbers at the two pointers with the fixed number is zero, record the triplet. Jul 30, 2024 · Solving the 3Sum Problem in Java and Go The “3Sum” problem is a classic coding challenge that involves finding all unique triplets in an array that add up to zero. Three Number Sum Problem Statement Given an array of integers, find all triplets in the array that sum up to a given target value. Oct 15, 2024 · Problem Statement: You are given an array of integers nums, which may contain positive, negative, or zero values. The goal is to find all unique triplets in the array that sum to zero. A triplet consists of three numbers, and the sum of these three numbers should be zero. e. lnnvgdlsqwmen6wwocqbjpwwvj1nasnlnmyrylqiei0jaoo