Day 4 of 133
Confidence intervals + bootstrapping + DSA Two Pointers
CIs, bootstrap, frequentist vs Bayesian; start the Two Pointers pattern.
DSA · NeetCode Two Pointers
- Valid PalindromeDSA · Two Pointers
Interview questions to prep
- How do you handle non-alphanumerics and case — what's your filter logic?
- What if the string is huge and streamed — can you process it without loading it all?
- Two Sum II Input Array IS SortedDSA · Two Pointers
Interview questions to prep
- What invariant do the two pointers preserve, and why does that prove correctness?
- Why is this O(n) and not O(n²) — what guarantees each element is visited a bounded number of times?
- Walk through edge cases: empty input, all duplicates, sorted vs unsorted.
- 3sumDSA · Two Pointers
Interview questions to prep
- How do you avoid duplicate triples without a set — what's the skip-duplicates pattern?
- Generalize to k-sum: what's the recursion, and what's the complexity?
Math · Confidence intervals & bootstrapping
Interview questions to prep
- What does a 95% confidence interval actually mean?
- Why is a 95% CI NOT 'a 95% probability the true value is in this range' under frequentist statistics?
- How would you build a CI for a click-through rate with N=1,000?
Interview questions to prep
- When is bootstrapping more useful than a parametric CI?
- Walk through bootstrapping a CI for the median.
- How does a permutation test compare to a t-test when assumptions are violated?
Interview questions to prep
- Compare frequentist confidence intervals vs Bayesian credible intervals.
- When does a Bayesian credible interval communicate uncertainty more naturally?
References & further reading