3Sum - Complete Tutorial

The 3-Sum problem is a classic algorithmic problem where the objective is to find all unique triplets in an array that sum up to a specific target value, usually zero. This problem is a popular interview question and is commonly used in coding challenges to test a candidate's understanding of arrays, sorting, and efficient algorithms.

The 3Sum problem can be divided into two categories based on whether the input array is sorted or unsorted.

3Sum on Unsorted Input

• All Triplets with Zero Sum
• All triplets with given sum
• Triplet Sum Closest to Given Sum
• Pythagorean Triplet
• All Pythagorean Triplets
• All Unique Triplets with Given Sum
• Triplets with Sum of 2 equal to 3rd

3Sum on Sorted Input

• 3 Sum – Triplet Sum in Array
• 3 Sum – All Distinct Triplets with given Sum in an Array
• 3 Sum – Triplet Sum Closest to Target
• Three closest elements from three sorted
• Triplet with given sum in BST
• Triplet in a Balanced BST with sum zero
• Count triplets with smaller sum

Miscellaneous Problems

• Maximum Sum Triplet
• Maximum product of a triplet