Challenge Archives

Past problems, top solvers, and full write-ups on GitHub

MonthChallengeTop Solver
#Jan
The Probabilistic Sieve
Feb 2, 2026·
Number TheoryProbabilityCombinatorics+1
SG
Samarth Gupta
GitHub
#Feb
The Round Lot Puzzle
Feb 16, 2026·
CombinatoricsModular ArithmeticMarket Microstructure+1
SC
Simanga Comfort Mchunu
GitHub
#Mar
The Coin Flip Race
Mar 2, 2026·
ProbabilityExpected Value
US
Ujjwal Sharma
GitHub
#Apr
The Crossing
Apr 1, 2026·
GreedyData Structures
—GitHub
#JanFeb 2, 2026

The Probabilistic Sieve

Number TheoryProbabilityCombinatoricsBitmasks
Top Solver
SG
Samarth Gupta
View on GitHub
#FebFeb 16, 2026

The Round Lot Puzzle

CombinatoricsModular ArithmeticMarket MicrostructureSubset Sum
Top Solver
SC
Simanga Comfort Mchunu
View on GitHub
#MarMar 2, 2026

The Coin Flip Race

ProbabilityExpected Value
Top Solver
US
Ujjwal Sharma
View on GitHub
#AprApr 1, 2026

The Crossing

GreedyData Structures
Top SolverNo submissions yet
View on GitHub