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Coding Challenges
5,893 curated questions across every arena — browse by topic, then jump into a live 3-minute battle to put them to the test.
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528 challenges matching your filters
- Code AnalysisBeginner
try/except catch
pythonbeginner - Code AnalysisBeginner
finally execution
pythonbeginner - Code AnalysisBeginner
assert failure
pythonbeginner - Code AnalysisBeginner
map with lambda
pythonbeginner - Code AnalysisBeginner
filter with lambda
pythonbeginner - Code AnalysisBeginner
Generator Yield
pythonbeginner - Code AnalysisBeginner
Generator Expression — Memory
pythonbeginner - Code AnalysisBeginner
zip pairs
pythonbeginner - Code AnalysisBeginner
Small int cache range
pythonbeginner - Code AnalysisBeginner
pathlib operations
pythonbeginner - Code AnalysisBeginner
json loads types
pythonbeginner - Code AnalysisBeginner
csv reader
pythonbeginner - Code AnalysisBeginner
StringIO write
pythonbeginner - Code AnalysisBeginner
Path parent
pythonbeginner - Code AnalysisBeginner
Dunder str
pythonbeginner - Code AnalysisBeginner
generator sum
pythonbeginner - Code AnalysisBeginner
deque appendleft
pythonbeginner - Code AnalysisBeginner
__name__ check
pythonbeginner - Code AnalysisBeginner
Module alias
pythonbeginner - Code AnalysisBeginner
from import — Namespace Pollution
pythonbeginner - Code AnalysisBeginner
sys.path existence
pythonbeginner - Code AnalysisBeginner
wildcard import
pythonbeginner - Code AnalysisBeginner
datetime format
pythonbeginner - Code AnalysisBeginner
timedelta calc
pythonbeginner - Code AnalysisBeginner
math.ceil
pythonbeginner - Code AnalysisBeginner
statistics mean
pythonbeginner - Code AnalysisBeginner
String Slicing Step
pythonbeginner - Code AnalysisBeginner
String Format Nesting
pythonbeginner - Code AnalysisBeginner
join with numbers
pythonbeginner - Code AnalysisBeginner
split and join
pythonbeginner - Code AnalysisBeginner
String Immutability
pythonbeginner - Code AnalysisBeginner
f-string number format
pythonbeginner - Code AnalysisBeginner
List Append Output
pythonbeginner - Code AnalysisBeginner
String Slicing
pythonbeginner - Code AnalysisBeginner
Range with Step
pythonbeginner - Code AnalysisBeginner
String Format
pythonbeginner - Code AnalysisBeginner
Multiple Assignment — Star Unpacking
pythonbeginner - Code AnalysisBeginner
Comparison Chaining
pythonbeginner - Code AnalysisBeginner
mock return_value
pythonbeginner - Code AnalysisBeginner
assertEqual output
pythonbeginner - Code AnalysisBeginner
Dict Merge 3.9+
code-analysisPythonlanguage - Code AnalysisBeginner
F-string Format Spec
code-analysisPythonlanguage - Code AnalysisBeginner
Reversed String
code-analysisPythonlanguage - Code AnalysisBeginner
Set Comprehension
code-analysisPythonlanguage - Code AnalysisBeginner
Star Unpacking
code-analysisPythonlanguage - Code AnalysisBeginner
Truthiness Edge Cases
code-analysisPythonlanguage - Code AnalysisBeginner
Unequal Zip
code-analysisPythonlanguage - Code AnalysisBeginner
NULL comparison bug
system-designdatabasessql - Code AnalysisBeginner
Unbounded SELECT without index
system-designdatabasesindexesreplication - Code AnalysisBeginner
Missing index on a foreign-key join
system-designdatabasesindexes - Code AnalysisBeginner
Cache key without entity version
system-designcachingcache-invalidation - Code AnalysisBeginner
Thundering herd on connection pool resize
system-designdatabasesconnection-pool - Code AnalysisBeginner
Read replica lag on user update
system-designreplicationconsistency - Code AnalysisBeginner
Snowflake clock rollback
system-designunique-idsnowflake - Code AnalysisBeginner
No timeout on downstream call
system-designavailabilityresilience - Code AnalysisBeginner
Unbounded result set in API
system-designapi-designpagination - Code AnalysisBeginner
Fixed-window boundary burst
system-designrate-limiting - Code AnalysisBeginner
Read-modify-write without atomicity
system-designconcurrencydistributed-counter - Code AnalysisBeginner
Writing to a replica
system-designdatabasesreplication - Code AnalysisBeginner
Cache aside stampede on hot key expiry
cachingstampedehot-key
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