Solving 3Sum using Two pointers.

Problem

Find triplets summing to zero.

Pattern

This problem demonstrates the Two pointers pattern.

Approach

Sort array, fix one element, two-pointer scan.

Solution 

  // Solution for 3Sum
// Pattern: Two pointers
// O(n²) time

Complexity

O(n²) time

Best Practices

  • Identify the pattern before coding — pattern recognition saves time
  • Handle edge cases: empty input, single element, duplicates
  • Use descriptive variable names even in timed interviews
  • Test with the provided examples plus one custom case