Debug Fast: Stress Tests & Triage
A WA-to-AC routine under the clock.
Debug Fast: Stress Tests & Triage is a free Coding Interview Prep lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Coding Interview Prep learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
The Clock Is Ticking
In a contest a wrong answer is a puzzle you must solve fast. A calm routine beats panicked guessing every single time. ⏱️
Read the Verdict First
Let the verdict guide you. WA means wrong logic, TLE means too slow, and RE points at a crash like an index error.
Triage TLE
For a TLE, recheck your complexity against the constraints. A hidden nested loop or slow input is usually the culprit.
Triage RE
A runtime error often means an out-of-range index, division by zero, or deep recursion. Reproduce it on a small input.
Triage WA
For a wrong answer, suspect edge cases first: empty input, N equal to 1, all-equal values, or the maximum bounds.
Write a Brute Force
Code a tiny, obviously correct brute force. It is too slow for the real limits but perfect as a source of truth.
Generate Random Tests
Write a small generator that prints random inputs within tiny bounds. Small cases expose bugs without overwhelming you.
import random
n = random.randint(1, 6)
print(n)
print(*[random.randint(1, 9) for _ in range(n)])Stress Test the Two
Run your solution and the brute force on the same random inputs and compare. The first mismatch is a shrunken failing case.
for _ in range(1000):
inp = gen()
if solve(inp) != brute(inp):
print("FAIL", inp); breakShrink the Counterexample
Once you have a failing case, make it as small as possible. A two-element bug is far easier to read than a hundred.
Print and Inspect State
Drop quick prints to stderr so they do not pollute your output. Watch your variables on the tiny failing case.
import sys
print("dp =", dp, file=sys.stderr)Know When to Move On
If a problem stalls you, switch to another and return later. Fresh eyes and saved time score more points overall.
Quick Check
You keep getting WA on a problem and cannot see why. What is the most reliable next step?
Recap
Read the verdict, triage by type, then stress test against a brute force to catch a small failing case. Stay calm and triage smart. 🧰
Frequently asked questions
Is the “Debug Fast: Stress Tests & Triage” lesson free?
Yes — the full text of “Debug Fast: Stress Tests & Triage” is free to read here on the web, and the Coding Interview Prep course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Coding Interview Prep course, upgrade to CoddyKit PRO.
What will I learn in “Debug Fast: Stress Tests & Triage”?
A WA-to-AC routine under the clock. You practise Coding Interview Prep with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Coding Interview Prep?
No prior experience is required. Coding Interview Prep on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Debug Fast: Stress Tests & Triage” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Coding Interview Prep lesson?
Yes. Every Coding Interview Prep lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Winning & Losing States in Games
- Nim and the Grundy Number
- Meet in the Middle
- Debug Fast: Stress Tests & Triage