How many problems should I solve before an interview?

150–250 problems distributed across the 12 patterns. Quality beats quantity — a deeply-understood two-pointers problem is worth 5 shallow ones.

How do I know when I'm ready?

You can solve a random problem from a pattern you haven't touched in two weeks, in under 30 minutes, while narrating. If silence or >30 minutes, you're not.

Should I use LeetCode, or something else?

LeetCode for problem access is fine. For structure, use a curriculum that ties problems to patterns. Random grinding leaves gaps.

What if I've been out of interview loops for 5+ years?

Expect 3 months minimum. The pattern library hasn't changed much, but the bar at top companies has risen. Budget 12 weeks and don't schedule loops before you're ready.

How does Alpha Code's prep differ from generic LeetCode grinding?

Every problem is tagged to a pattern and slotted into your diagnostic weak-set. You don't pick problems randomly — the system picks them for you based on what you just got wrong.

Guide · Technical

Technical interview prep — what actually works, beyond the grind.

TL;DR

Technical interview prep is three layers: pattern fluency (you can recognize which of 12 patterns a problem uses), timed execution (you can code it in 45 minutes while talking), and communication (you narrate without making the interviewer pull it out of you). Most candidates over-drill layer 1 and under-drill layers 2 and 3.

Who this is for

Any candidate preparing for a coding interview loop — FAANG, mid-tier tech, fintech, or startups.

Time commitment

8–12 weeksof structured prep. Less if you've been interviewing recently; more from a cold start.

Layer 1: Pattern fluency

The 12 canonical patterns cover 90%+ of interview problems. Fluency means you can name the pattern from the problem statement in under 2 minutes. If you can't, you'll improvise — and improvisation fails under the 45-minute clock.

Layer 2: Timed execution

Once you've drilled a pattern, the next bottleneck is speed. Set a 45-minute timer, solve a problem end-to-end (clarify → approach → code → test), and grade yourself honestly. If you finished but didn't test, you didn't finish.

Layer 3: Communication

The silent solver is the failing solver. Even if your code is correct, if the interviewer can't follow your reasoning, they score you as 'unclear thinker.' Narrating is a skill — practice it in mocks, not in solo sessions.

Common anti-patterns

Grinding LeetCode Hard before you have pattern fluency. Solving silently. Skipping the test phase. Memorizing solutions instead of approaches. All of these feel productive and produce no signal to a real interviewer.

Patterns to prioritize

Drill these first. Each links to a dedicated pattern page with template, scenarios, and reference code.

Dynamic ProgrammingBreak an overlapping-subproblem problem into a recurrence and cache results.Graph BFS / DFSBreadth-first for shortest unweighted paths; depth-first for exhaustive traversal.Sliding WindowMaintain a contiguous range and slide its boundaries to avoid recomputation.BacktrackingDFS through a decision tree with pruning and state restoration.Binary Search on AnswerWhen a predicate is monotonic over the answer space, binary search the answer itself.

Frequently asked questions

How many problems should I solve before an interview?: 150–250 problems distributed across the 12 patterns. Quality beats quantity — a deeply-understood two-pointers problem is worth 5 shallow ones.
How do I know when I'm ready?: You can solve a random problem from a pattern you haven't touched in two weeks, in under 30 minutes, while narrating. If silence or >30 minutes, you're not.
Should I use LeetCode, or something else?: LeetCode for problem access is fine. For structure, use a curriculum that ties problems to patterns. Random grinding leaves gaps.
What if I've been out of interview loops for 5+ years?: Expect 3 months minimum. The pattern library hasn't changed much, but the bar at top companies has risen. Budget 12 weeks and don't schedule loops before you're ready.
How does Alpha Code's prep differ from generic LeetCode grinding?: Every problem is tagged to a pattern and slotted into your diagnostic weak-set. You don't pick problems randomly — the system picks them for you based on what you just got wrong.

Run the free diagnostic.

Ten-minute patterns quiz. No card. Personalized loop starts on the other side.

Start the diagnostic