🌍 Why This Document Exists

This document trains engineering judgment, not syntax.

Real interviews test:

• how you combine conditions
• how you eliminate wrong paths
• how you protect systems with logic

If you master this → you think like a senior Python engineer.

🧠 Python Algorithm Thinking — 20 Advanced Logic Puzzles

Rules:

• No shortcuts
• Read carefully
• Think in conditions

🟢 Puzzle 1 — Smart API Throttling

API request has:

requests = [
    {"user":"A","count":90,"premium":False},
    {"user":"B","count":120,"premium":True},
    {"user":"C","count":120,"premium":False},
]

Rules:

• Block if count > 100
• BUT allow if premium == True

Task:
Return users that are blocked.

blocked = []

for r in requests:
    if r["count"] > 100 and not r["premium"]:
        blocked.append(r["user"])

print(blocked)

🟢 Puzzle 2 — Secure Login Validator

A login attempt is valid if:

• username exists
• password matches
• account is active OR admin override is true

user = {
  "exists": True,
  "password_ok": True,
  "active": False,
  "admin_override": True
}

Task:
Return True / False.

valid = (
    user["exists"]
    and user["password_ok"]
    and (user["active"] or user["admin_override"])
)

print(valid)

🟢 Puzzle 3 — Production Error Escalation

Error should be escalated if:

• severity ≥ 8
• AND (service is "payment" OR "auth")
• AND NOT during maintenance

error = {"sev":9,"service":"payment","maintenance":False}

if (
    error["sev"] >= 8
    and error["service"] in ("payment","auth")
    and not error["maintenance"]
):
    print("Escalate")

🟡 Puzzle 4 — Smart Cache Usage

Use cache if:

• cache exists
• AND (data fresh OR forced_cache=True)

cache = {"exists":True,"fresh":False}
forced_cache = True

use_cache = (
    cache["exists"]
    and (cache["fresh"] or forced_cache)
)

print(use_cache)

🟡 Puzzle 5 — Fraud Detection Rule

Transaction is suspicious if:

• amount > 10_000
• OR (amount > 3_000 AND country not trusted)
• AND NOT internal_transfer

tx = {"amount":5000,"trusted":False,"internal":False}

if (
    (tx["amount"] > 10000
    or (tx["amount"] > 3000 and not tx["trusted"]))
    and not tx["internal"]
):
    print("Suspicious")

🟡 Puzzle 6 — Multi-Level Access Control

Access granted if:

• role is "admin"
• OR (role "dev" AND env "staging")
• OR (role "viewer" AND read_only=True)

user = {"role":"dev","env":"staging","read_only":False}

if (
    user["role"] == "admin"
    or (user["role"] == "dev" and user["env"] == "staging")
    or (user["role"] == "viewer" and user["read_only"])
):
    print("Access granted")

🟡 Puzzle 7 — Intelligent Retry Logic

Retry request if:

• status >= 500
• AND retries < 3
• AND NOT timeout

req = {"status":502,"retries":2,"timeout":False}

if (
    req["status"] >= 500
    and req["retries"] < 3
    and not req["timeout"]
):
    print("Retry")

🔵 Puzzle 8 — Data Pipeline Drop Rule

Drop record if:

• missing required field
• OR invalid format
• OR (late arrival AND not backfill)

rec = {"missing":False,"invalid":False,"late":True,"backfill":False}

if (
    rec["missing"]
    or rec["invalid"]
    or (rec["late"] and not rec["backfill"])
):
    print("Drop")

🔵 Puzzle 9 — Alert Noise Reduction

Send alert if:

• severity ≥ 7
• AND (new_error OR error_rate > threshold)
• AND NOT already_alerted

if (
    sev >= 7
    and (new_error or rate > threshold)
    and not alerted
):
    print("Alert")

🔵 Puzzle 10 — Smart Autoscaling Decision

Scale up if:

• cpu > 70 AND mem > 70
• OR queue > 1000
• AND NOT maintenance

if (
    ((cpu > 70 and mem > 70) or queue > 1000)
    and not maintenance
):
    print("Scale up")

🔴 Puzzle 11 — Complex Log Filtering

Keep log if:

• level is ERROR or WARN
• AND service not deprecated
• AND (env is prod OR flagged)

if (
    log["level"] in ("ERROR","WARN")
    and not log["deprecated"]
    and (log["env"] == "prod" or log["flagged"])
):
    kept.append(log)

🔴 Puzzle 12 — Deployment Gate

Allow deploy if:

• tests passed
• AND security approved
• AND (low_risk OR manager_approved)

if (
    tests_ok
    and security_ok
    and (low_risk or manager_ok)
):
    print("Deploy")

🔴 Puzzle 13 — Feature Flag Evaluation

Enable feature if:

• flag_on
• AND user_beta
• AND NOT region_blocked

if flag and beta and not blocked:
    enable()

🔴 Puzzle 14 — Dead Letter Queue Rule

Send to DLQ if:

• retries exhausted
• OR malformed payload
• AND NOT manual_override

if (
    (retries == 0 or malformed)
    and not manual_override
):
    send_dlq()

🔴 Puzzle 15 — AI Model Safety Gate

Allow response if:

• confidence > 0.9
• AND NOT hallucinated
• AND (verified_source OR human_reviewed)

if (
    conf > 0.9
    and not hallucinated
    and (verified or reviewed)
):
    respond()

🟣 Puzzle 16 — Distributed Lock Acquisition

Acquire lock if:

• lock free
• OR expired
• AND requester authorized

if (
    (free or expired)
    and authorized
):
    acquire()

🟣 Puzzle 17 — Multi-Region Failover

Failover if:

• primary down
• AND secondary healthy
• AND NOT maintenance_window

if primary_down and secondary_ok and not maintenance:
    failover()

🟣 Puzzle 18 — Abuse Detection

Block user if:

• reports > 5
• AND (spam OR harassment)
• AND NOT verified_user

if reports > 5 and (spam or harassment) and not verified:
    block()

🟣 Puzzle 19 — Financial Transaction Approval

Approve if:

• balance sufficient
• AND not frozen
• AND (trusted_merchant OR small_amount)

if balance >= amount and not frozen and (trusted or amount < 50):
    approve()

🟣 Puzzle 20 — Senior-Level Thinking

Explain (no code):
Why grouping conditions incorrectly can cause:

• security bugs
• outages
• financial loss

🏁 Final Truth

If you master logic composition,
you master engineering power.

Teach this. Spread this. Make engineers better.