DSA pattern
Two Pointers
The two pointers technique uses two indices to iterate through a data structure, often from opposite ends or at different speeds. This pattern is essential for sorted array problems, palindrome checking, and finding pairs that meet certain criteria.
When to use
5 signals- 01Working with sorted arrays or strings
- 02Finding pairs or triplets with a target sum
- 03Checking for palindromes
- 04Removing duplicates in-place
- 05Container with most water problems
In interviews, call out the pattern early. It helps interviewers follow your reasoning and keeps your implementation focused. After solving, explain tradeoffs in plain language: why this approach is efficient, where it can break, and what edge cases you would test first.
Practice problems
5 listed- 01Two Sum IIPractice →
- 02Valid PalindromePractice →
- 03Container With Most WaterPractice →
- 043SumPractice →
- 05Trapping Rain WaterPractice →
Build a review loop
Treat each pattern as a repeating cycle, not a one-time read. Solve a fresh problem today, revisit the same pattern in 2-3 days, and run one timed attempt at the end of the week. This turns short-term familiarity into reliable recall for live interviews.
When reviewing, re-derive the core steps from scratch before checking a reference solution. If you can explain the state transitions and edge cases clearly, you are much more likely to execute well under interview pressure.