Coding Interview Preparation in 30 Days: A Focused Plan
Thirty days is not enough to learn computer science from zero. It is enough to make a serious jump if you already write basic code and can commit 1.5–3 hours most days. This plan is for candidates with a deadline: a recruiter screen, an upcoming onsite loop, or a campus season. The goal is not 300 problems. The goal is pattern coverage, timed execution, and clear communication.Who this plan is for
Good fit- You know loops, functions, arrays, hash maps at a basic level
- You can spare ~2 hours/day (or 3 on weekends)
- You have interviews in roughly 3–6 weeks
- Brand-new to programming → spend 4–6 weeks on fundamentals first
- Targeting only senior design interviews → this is DSA-coding focused
Rules that make 30 days work
- One pattern family per day in weeks 1–3 (no random free-for-all).
- Struggle timer: 15–20 minutes before hints; 40 minutes max before reading a solution—then re-solve next day.
- Re-solve > new solve. Every fourth day is revision.
- Speak aloud on at least three problems per week.
- Track patterns, not ego metrics.
Daily session template (90–120 minutes)
| Block | Time | Action |
|---|---|---|
| Warm-up | 10 min | Easy problem or quiz on yesterday’s pattern |
| Focus solve | 40–50 min | 1 medium (or 2 easies if stuck early) |
| Second rep | 25–35 min | Related problem or harder variant |
| Notes | 10 min | Pattern card: signals, template, pitfalls, complexity |
| Cool-down | 5–10 min | Spaced review of 3 flash prompts |
If you only have 60 minutes: warm-up + one medium + notes.
30-day calendar
Week 1 — Linear structures & hashing
| Day | Focus |
|---|---|
| 1 | Arrays + Big O refresh; 2 easies |
| 2 | Two pointers (pair problems, reverse, partitions) |
| 3 | Sliding window (fixed + variable) |
| 4 | Revision day (re-solve days 2–3 cold) |
| 5 | Hash maps (two sum family, frequencies, anagrams) |
| 6 | Strings (windows + counting) |
| 7 | Timed mock: 2 problems in 70 minutes |
Week 2 — Stacks, binary search, intervals, lists
| Day | Focus |
|---|---|
| 8 | Stack (parentheses, next greater) |
| 9 | Monotonic stack / queue intro problems |
| 10 | Binary search on arrays |
| 11 | Revision |
| 12 | Binary search on answer (monotonic predicate) |
| 13 | Intervals (merge, overlaps) + sorting as tool |
| 14 | Linked list essentials (reverse, cycle, merge) + mock |
Week 3 — Trees & graphs
| Day | Focus |
|---|---|
| 15 | Binary tree DFS templates |
| 16 | BFS level order + tree basics |
| 17 | BST property problems |
| 18 | Revision |
| 19 | Graph representations + BFS |
| 20 | DFS graphs, components, cycle basics |
| 21 | Grid graphs + timed mock |
Week 4 — Heaps, DP lite, interview polish
| Day | Focus |
|---|---|
| 22 | Heaps / top K |
| 23 | DP 1D (stairs, robber, climbing cost) |
| 24 | DP knapsack-ish (coin change family) |
| 25 | Revision of weakest week |
| 26 | Mixed mediums (company-tagged if available) |
| 27 | Behavioral + approach rehearsal (STAR stories + talk-throughs) |
| 28 | Full mock interview (friend or self-record) |
| 29 | Error-log only (no new patterns) |
| 30 | Light review + sleep early |
Pattern cards (keep them tiny)
Example card:Pattern: Sliding window (variable)
Signals: longest/shortest substring with constraint
Template: move R, while invalid move L, update answer
Pitfalls: when to update answer; off-by-one on counts
Time: O(n) Space: O(k) alphabet/mapIf a card needs more than half a page, you do not understand it yet—simplify.
Communication script (use in every mock)
- Restate the problem and ask a clarifying question
- Give a brute force
- Propose optimized approach and complexity
- Code
- Trace an example
- Edge cases
Interviewers hire the script as much as the code.
What to skip in a 30-day crunch
- Advanced segment trees, heavy computational geometry
- Competitive programming only tricks
- Jumping to hard problems to feel brave
- Rewatching 10-hour courses from zero mid-plan
Depth on core mediums beats tourism on hards.
Metrics dashboard (weekly)
| Metric | Target |
|---|---|
| Patterns with a card | +5 to +7 / week |
| Problems fully re-solved cold | ≥6 / week |
| Timed sessions | ≥2 / week |
| Talk-aloud problems | ≥3 / week |
| Sleep < 6 hours days | 0 (non-negotiable near interviews) |
If cold re-solves are rare, you are consuming solutions, not training.
Using AI during the 30 days
Allowed:- Explaining a concept after you attempt
- Generating extra tests
- Reviewing your code for clarity
Not allowed on focus solves:
- “Write the solution” as step one
On interview day, assume AI may be limited. Train your brain accordingly.
Minimal resource stack
- One problem platform
- One notes file
- One timer
- Optional: short gamified drills for pattern recognition on low-energy days
Switching five courses in 30 days is self-sabotage.
Low-energy day protocol
You will have bad days. Do not zero them. Minimum viable day (35–40 min):- 10 min quiz/flash on a weak pattern
- 20 min re-solve one old problem
- 5 min update error log
Streaks of minimum days beat heroic days followed by collapse.
How PixoQuest supports a 30-day sprint
Interview prep fails when fundamentals get fuzzy under fatigue. PixoQuest’s short DSA lessons and mini-games are ideal warm-ups and low-energy days: complexity, arrays, and pattern recognition in minutes, with XP and streaks to keep the calendar green. Use PixoQuest for the first 10–15 minutes of a session or on exhausted evenings; use your coding platform for full implementations and mocks. That split keeps the 30-day plan human.After day 30
- If interviews continue: maintain 4 days/week mixed practice
- Build a “company pack” from recent question reports
- Add system design only if your loop requires it
