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Complete · 30 Days

· 30-day option

An intense one-month pass through the whole bank — every topic and all coding, interleaved so each one keeps coming back instead of being crammed once, ramping gently from easy to hard. About six problems a day.

Sign in to track your progress — each problem checks off as you solve it.

01Brain Teasers

2
Trailing Zeros in 100!
Brain TeasersGoldman SachsJ.P. Morgan
52%Easy5
Clock Hands at 3:15
Brain TeasersMorgan StanleyBarclays
58%Easy6
Sum 1 to 100
Brain TeasersJane StreetGoldman Sachs
72%Easy9
Last Digit of 2^100
Brain TeasersGoldman SachsMorgan Stanley
60%Easy13
Handshakes at a Party
Brain TeasersGoldman Sachs
67%Easy3
Two Eggs, 100 Floors
Brain TeasersGoogleGoldman Sachs
31%Medium4
Horse Race — Top 3
Brain TeasersGoogleTwo Sigma
42%Medium7
100 Lockers
Brain TeasersGoogleTwo Sigma
62%Medium8
Poisoned Wine
Brain TeasersGoogleJane Street
35%Medium10
Mislabeled Jars
Brain TeasersJane StreetOptiver
59%Medium11
Burning Ropes — 45 Minutes
Brain TeasersGoldman SachsMorgan Stanley
76%Medium14
Bridge Crossing
Brain TeasersGoogleJane Street
49%Medium15
Ants on a Triangle
Brain TeasersGoldman SachsOptiver
84%Medium16
Water Jugs
Brain TeasersGoogle
74%Medium17
Three Switches
Brain TeasersGoldman SachsMorgan Stanley
70%Medium20
The Mutilated Chessboard
Brain TeasersGoogleHRT
67%Medium1
Screwy Pirates
Brain TeasersJane StreetOptiver
51%Hard12
12 Balls, One Odd
Brain TeasersCitadelJane StreetTwo Sigma
45%Hard18
The Camel and the Bananas
Brain TeasersJane StreetGoogle
40%Hard19
The Blue-Eyed Islanders
Brain TeasersJane StreetTwo Sigma
40%Hard

02Probability

21
Coin Toss — Two Heads
ProbabilityJane Street
53%Easy22
Monty Hall
ProbabilityGoldman SachsMorgan Stanley
56%Easy25
Flips Until First Head
ProbabilityOptiverIMC Trading
69%Easy27
Two Dice Sum to 7
ProbabilityOptiverIMC Trading
85%Easy32
Two Children
ProbabilityGoldman SachsMorgan Stanley
66%Easy38
Expected Rolls for a Six
ProbabilityOptiverIMC Trading
79%Easy39
At Least One Six
ProbabilitySIG / SusquehannaOptiver
60%Easy23
Roll Until All Six Faces
ProbabilityGoogleTwo Sigma
41%Medium24
Birthday Problem
ProbabilityGoldman SachsCitadel
52%Medium26
Drunk Passenger
ProbabilityJane StreetCitadel
55%Medium28
Bayes — Disease Test
ProbabilityGoldman SachsTwo Sigma
55%Medium29
Broken Stick Triangle
ProbabilityJane StreetCitadel
43%Medium30
Top Two Aces
ProbabilitySIG / SusquehannaOptiver
63%Medium31
Hat Check
ProbabilityJane StreetDE Shaw
72%Medium33
Expected Max of Two Dice
ProbabilityOptiverIMC Trading
41%Medium34
Russian Roulette — Spin?
ProbabilityJane StreetCitadel
62%Medium35
Expected Min of Two Dice
ProbabilityOptiverSIG / Susquehanna
71%Medium36
Poisson — No Arrivals
ProbabilityTwo SigmaJump Trading
69%Medium37
Exponential Survival
ProbabilityDE ShawMorgan Stanley
52%Medium40
Expected Max of Two Uniforms
ProbabilityJane StreetCitadel
51%Medium43
The Shorter Piece
ProbabilityOptiverMorgan Stanley
52%Medium44
The Secretary Problem
ProbabilityJane StreetDE Shaw
44%Medium45
Galileo’s Three Dice
ProbabilityOptiverIMC Trading
58%Medium41
The Tuesday Boy
ProbabilityJane StreetSIG / Susquehanna
44%Hard42
The 100 Prisoners Problem
ProbabilityJane StreetTwo Sigma
45%Hard

03Stochastic Processes

49
Variance of Brownian Motion
Stochastic ProcessesGoldman SachsMorgan Stanley
69%Easy46
Flips Until Two Heads in a Row
Stochastic ProcessesJane StreetCitadel
44%Medium47
Gambler’s Ruin
Stochastic ProcessesJane StreetSIG / Susquehanna
72%Medium50
Covariance of Brownian Motion
Stochastic ProcessesGoldman SachsTwo Sigma
65%Medium52
Random Walk Recurrence
Stochastic ProcessesTwo SigmaDE Shaw
69%Medium53
Quadratic Variation of BM
Stochastic ProcessesGoldman SachsTwo Sigma
66%Medium57
Hitting 3 Before 0
Stochastic ProcessesCitadelMorgan Stanley
77%Medium58
Two Poisson Streams
Stochastic ProcessesJump TradingHRT
70%Medium59
How Long Until Ruin or Riches
Stochastic ProcessesOptiverSIG / Susquehanna
57%Medium60
Half-Life of Mean Reversion
Stochastic ProcessesAQR CapitalMillennium Management
64%Medium48
Expectation of GBM
Stochastic ProcessesGoldman SachsMorgan Stanley
59%Hard51
Expected Flips for HTH
Stochastic ProcessesJane StreetSIG / Susquehanna
45%Hard54
Random Walk — Expected Steps
Stochastic ProcessesJane StreetTwo Sigma
57%Hard55
Expected Running Max of BM
Stochastic ProcessesGoldman SachsDE Shaw
54%Hard56
The Ballot Problem
Stochastic ProcessesJane StreetDE Shaw
47%Hard61
Reflection Principle for the Maximum
Stochastic ProcessesCitadelDE Shaw
50%Hard

04Calculus & Linear Algebra

62
Definite Integral of x²
Calculus & Linear AlgebraGoldman Sachs
78%Easy63
Limit of sin(x)/x
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
91%Easy68
Geometric Series
Calculus & Linear AlgebraGoldman Sachs
86%Easy69
Limit of (1+1/n)^n
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
55%Easy71
L'Hôpital — (eˣ−1)/x
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
84%Easy72
Derivative of ln(x)
Calculus & Linear AlgebraGoldman Sachs
85%Easy73
Sum of First 10 Squares
Calculus & Linear AlgebraJane StreetTwo Sigma
87%Easy74
Trace = Sum of Eigenvalues
Calculus & Linear AlgebraTwo SigmaGoldman Sachs
82%Easy75
Determinant = Product of Eigenvalues
Calculus & Linear AlgebraTwo SigmaDE Shaw
71%Easy77
Approximate cos(0.1)
Calculus & Linear AlgebraJane StreetOptiver
84%Easy64
Eigenvalues of a 2×2
Calculus & Linear AlgebraGoldman SachsCitadel
80%Medium65
Gaussian Integral
Calculus & Linear AlgebraGoldman SachsTwo Sigma
43%Medium66
Derivative of xˣ
Calculus & Linear AlgebraJane StreetCitadel
83%Medium70
Integral of x·e^(−x)
Calculus & Linear AlgebraGoldman SachsTwo Sigma
74%Medium76
Integrate x·eˣ
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
73%Medium67
Maximize x^(1/x)
Calculus & Linear AlgebraJane StreetSIG / Susquehanna
51%Hard

05Algorithms & Numerical

78
Two SumLeetCode
Algorithms & NumericalGoogleDE Shaw
Easy87
Monte Carlo — Estimate π
Algorithms & NumericalGoldman SachsTwo Sigma
65%Easy88
Newton’s Method for √2
Algorithms & NumericalGoldman SachsJane Street
79%Easy97
Nim GameLeetCode
Algorithms & NumericalJane StreetSIG / Susquehanna
Easy79
Product of Array Except SelfLeetCode
Algorithms & NumericalTwo SigmaHRT
Medium81
Kth Largest ElementLeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium83
Maximum Subarray (Kadane)LeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium84
Random Pick with WeightLeetCode
Algorithms & NumericalCitadelTwo Sigma
Medium85
Shuffle an Array (Fisher-Yates)LeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium86
Best Time to Buy and Sell StockLeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium89
Rand10() from Rand7()LeetCode
Algorithms & NumericalJane StreetOptiver
Medium90
Coin Change (DP)LeetCode
Algorithms & NumericalGoogleDE Shaw
Medium92
Online Stock SpanLeetCode
Algorithms & NumericalCitadel SecuritiesHRT
Medium93
Time-Based Key-Value StoreLeetCode
Algorithms & NumericalTwo SigmaJump Trading
Medium94
Best Time to Buy and Sell Stock IILeetCode
Algorithms & NumericalOptiverJane Street
Medium95
Gas StationLeetCode
Algorithms & NumericalJane StreetCitadel
Medium96
Jump GameLeetCode
Algorithms & NumericalGoogleDE Shaw
Medium98
Predict the WinnerLeetCode
Algorithms & NumericalJane StreetOptiver
Medium99
LRU CacheLeetCode
Algorithms & NumericalTwo SigmaHRT
Medium100
Longest Increasing SubsequenceLeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium102
Course ScheduleLeetCode
Algorithms & NumericalGoogleDE Shaw
Medium103
Number of IslandsLeetCode
Algorithms & NumericalGoogleTwo Sigma
Medium80
Trapping Rain WaterLeetCode
Algorithms & NumericalJane StreetCitadel Securities
Hard82
Sliding Window MaximumLeetCode
Algorithms & NumericalHRTJump Trading
Hard91
Median of Two Sorted ArraysLeetCode
Algorithms & NumericalGoogleTwo Sigma
Hard101
Find Median from Data StreamLeetCode
Algorithms & NumericalTwo SigmaCitadel
Hard

06Finance

104
Put-Call Parity
FinanceGoldman SachsMorgan Stanley
66%Easy107
Zero-Coupon Bond Price
FinanceGoldman SachsPIMCO
63%Easy108
Futures Fair Value
FinanceGoldman SachsOptiver
63%Easy109
Duration & Price Sensitivity
FinanceGoldman SachsJ.P. MorganPIMCO
72%Easy110
Perpetuity Value
FinanceGoldman SachsJ.P. Morgan
61%Easy111
Rule of 72
FinanceGoldman SachsMorgan Stanley
71%Easy114
Coupon Equals Yield
FinanceGoldman SachsPIMCO
64%Easy115
Current Yield
FinanceBarclaysMorgan Stanley
64%Easy118
Duration and a Rate Move
FinancePIMCOBlackRock
49%Easy120
Real Rate of Return
FinancePIMCOCitadel
62%Easy105
Black-Scholes ATM Call
FinanceGoldman SachsMorgan Stanley
72%Medium106
Risk-Neutral Probability
FinanceGoldman SachsJ.P. Morgan
81%Medium112
Gordon Growth Model
FinanceGoldman SachsMorgan Stanley
62%Medium113
Implied Forward Rate
FinanceJ.P. MorganBarclays
65%Medium116
Forward Price with a Dividend Yield
FinanceJ.P. MorganCitadel
65%Medium117
FX Forward by Interest Parity
FinanceGoldman SachsBarclays
65%Medium119
Present Value of an Annuity
FinanceMorgan StanleyJ.P. Morgan
56%Medium

07Options & Greeks

121
Delta of an ATM Call
Options & GreeksOptiverIMC Trading
61%Easy122
Delta of a Forward
Options & GreeksOptiverIMC Trading
73%Easy124
Most Negative Put Delta
Options & GreeksGoldman SachsOptiver
66%Easy126
Sign & Peak of Vega
Options & GreeksOptiverIMC Trading
74%Easy127
Delta Hedging
Options & GreeksOptiverCitadel Securities
76%Easy130
How Dear Can a Call Be?
Options & GreeksJane StreetAkuna Capital
76%Easy132
Find the Put from Parity
Options & GreeksGoldman SachsMorgan Stanley
58%Easy133
Delta of a Deep ITM Call
Options & GreeksIMC TradingOptiver
74%Easy135
Straddle Breakeven
Options & GreeksSIG / SusquehannaAkuna Capital
74%Easy136
Covered Call Max Profit
Options & GreeksMorgan StanleyIMC Trading
72%Easy123
Gamma Near Expiry
Options & GreeksOptiverIMC Trading
66%Medium125
Sign of Theta
Options & GreeksOptiverSIG / Susquehanna
71%Medium128
Early Exercise of a Call
Options & GreeksGoldman SachsMorgan Stanley
71%Medium129
Delta of an ATM Straddle
Options & GreeksOptiverIMC TradingSIG / Susquehanna
73%Medium131
Value of a Box Spread
Options & GreeksOptiverCitadel Securities
69%Medium134
Worst Case with a Protective Put
Options & GreeksBarclaysJ.P. Morgan
69%Medium

08Market Making & Games

137
Make a Market on Two Dice
Market Making & GamesOptiverSIG / Susquehanna
87%Easy143
Odds to Probability
Market Making & GamesFlow TradersOptiver
39%Easy148
Triangular FX Arbitrage
Market Making & GamesFlow TradersIMC Trading
68%Easy150
Piano Tuners in Chicago
Market Making & GamesOptiverIMC Trading
65%Easy151
Skewing Off an Inventory
Market Making & GamesOptiverFlow Traders
76%Easy153
The House Edge in European Roulette
Market Making & GamesSIG / SusquehannaFive Rings
52%Easy138
Fair Value of a Loaded Die
Market Making & GamesOptiverIMC Trading
68%Medium139
Roll, Keep or Re-roll
Market Making & GamesJane StreetSIG / Susquehanna
45%Medium141
Two Bookmakers, One Arbitrage
Market Making & GamesSIG / SusquehannaFlow Traders
55%Medium142
The Bookmaker’s Edge
Market Making & GamesSIG / SusquehannaDRW
54%Medium145
Kelly with 2-to-1 Odds
Market Making & GamesSIG / SusquehannaDRW
40%Medium146
Two-Thirds of the Average
Market Making & GamesJane StreetOptiver
65%Medium149
The St. Petersburg Game
Market Making & GamesJane StreetTwo Sigma
62%Medium154
The Doubling “System”
Market Making & GamesSIG / SusquehannaFive Rings
59%Medium140
The Red–Black Card Game
Market Making & GamesJane StreetCitadel Securities
39%Hard144
Quoting Against Informed Flow
Market Making & GamesCitadel SecuritiesSIG / Susquehanna
46%Hard147
Shading a First-Price Bid
Market Making & GamesJane StreetDE Shaw
55%Hard152
The Two-Envelope Paradox
Market Making & GamesJane Street
51%Hard

09Portfolio & Risk

155
Sharpe Ratio
Portfolio & RiskGoldman SachsAQR Capital
83%Easy164
Portfolio Beta
Portfolio & RiskGoldman SachsAQR Capital
86%Easy169
Information Ratio
Portfolio & RiskBlackRockMillennium Management
76%Easy170
Beta of a Portfolio
Portfolio & RiskJ.P. MorganBlackRock
76%Easy171
Sortino Ratio
Portfolio & RiskMan GroupMillennium Management
76%Easy156
Two-Asset Portfolio Volatility
Portfolio & RiskGoldman SachsAQR Capital
44%Medium157
Value at Risk (Normal)
Portfolio & RiskGoldman SachsMorgan StanleyMillennium Management
54%Medium158
CVaR / Expected Shortfall
Portfolio & RiskAQR CapitalTwo Sigma
52%Medium159
Diversification & Sharpe
Portfolio & RiskAQR CapitalCitadel
52%Medium160
Maximum Drawdown
Portfolio & RiskCitadelTwo SigmaMan Group
52%Medium161
Kelly Criterion
Portfolio & RiskCitadelJane Street
59%Medium162
VaR Time Scaling
Portfolio & RiskGoldman SachsMorgan Stanley
52%Medium163
Minimum-Variance Weight
Portfolio & RiskAQR CapitalBlackRock
52%Medium165
Annualizing Sharpe
Portfolio & RiskTwo SigmaAQR Capital
52%Medium166
The Diversification Floor
Portfolio & RiskBlackRockAQR Capital
52%Medium167
Minimum-Variance Hedge Ratio
Portfolio & RiskGoldman SachsPIMCO
52%Medium168
Two-Asset Risk Parity
Portfolio & RiskAQR CapitalMan Group
52%Medium

10Statistics

173
Variance of Uniform(0,1)
StatisticsGoldman SachsCitadel
71%Easy174
OLS Slope
StatisticsTwo SigmaAQR Capital
90%Easy175
Variance of a Sum
StatisticsGoldman SachsMorgan Stanley
63%Easy176
Central Limit Theorem
StatisticsGoldman SachsMorgan Stanley
74%Easy177
MLE of a Coin
StatisticsTwo SigmaDE Shaw
85%Easy179
Range of Correlation
StatisticsGoldman SachsCitadel
85%Easy180
Variance of a Scaled Variable
StatisticsGoldman Sachs
84%Easy183
Width of a 95% Confidence Interval
StatisticsGoldman SachsBlackRock
45%Easy184
From Correlation to R²
StatisticsTwo SigmaAQR Capital
60%Easy187
A One-Sample z-Statistic
StatisticsMorgan StanleyGoldman Sachs
75%Easy172
Correlation of X and X²
StatisticsTwo SigmaDE Shaw
74%Medium178
Covariance of a Linear Transform
StatisticsGoldman SachsAQR Capital
74%Medium181
Variance of the Sample Mean
StatisticsTwo SigmaDE Shaw
63%Medium182
The German Tank Problem
StatisticsTwo SigmaDE Shaw
69%Medium185
Correlation of X with X + Y
StatisticsJane StreetCitadel
57%Medium186
Median of an Exponential
StatisticsDE ShawJump Trading
64%Medium188
Simpson’s Paradox
StatisticsTwo SigmaCitadel
69%Medium
Follow as a 30-day schedule

Interleaved, easy → hard, mixed daily

1
Day 1

Coding · Brain teasers · Finance

78
Two SumLeetCode
Algorithms & NumericalGoogleDE Shaw
Easy21
Coin Toss — Two Heads
ProbabilityJane Street
53%Easy2
Trailing Zeros in 100!
Brain TeasersGoldman SachsJ.P. Morgan
52%Easy137
Make a Market on Two Dice
Market Making & GamesOptiverSIG / Susquehanna
87%Easy104
Put-Call Parity
FinanceGoldman SachsMorgan Stanley
66%Easy155
Sharpe Ratio
Portfolio & RiskGoldman SachsAQR Capital
83%Easy173
Variance of Uniform(0,1)
StatisticsGoldman SachsCitadel
71%Easy
2
Day 2

Coding · Brain teasers · Calculus

62
Definite Integral of x²
Calculus & Linear AlgebraGoldman Sachs
78%Easy121
Delta of an ATM Call
Options & GreeksOptiverIMC Trading
61%Easy49
Variance of Brownian Motion
Stochastic ProcessesGoldman SachsMorgan Stanley
69%Easy87
Monte Carlo — Estimate π
Algorithms & NumericalGoldman SachsTwo Sigma
65%Easy22
Monty Hall
ProbabilityGoldman SachsMorgan Stanley
56%Easy5
Clock Hands at 3:15
Brain TeasersMorgan StanleyBarclays
58%Easy143
Odds to Probability
Market Making & GamesFlow TradersOptiver
39%Easy
3
Day 3

Coding · Calculus · Finance

107
Zero-Coupon Bond Price
FinanceGoldman SachsPIMCO
63%Easy164
Portfolio Beta
Portfolio & RiskGoldman SachsAQR Capital
86%Easy174
OLS Slope
StatisticsTwo SigmaAQR Capital
90%Easy63
Limit of sin(x)/x
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
91%Easy122
Delta of a Forward
Options & GreeksOptiverIMC Trading
73%Easy46
Flips Until Two Heads in a Row
Stochastic ProcessesJane StreetCitadel
44%Medium88
Newton’s Method for √2
Algorithms & NumericalGoldman SachsJane Street
79%Easy
4
Day 4

Probability · Coding · Brain teasers

25
Flips Until First Head
ProbabilityOptiverIMC Trading
69%Easy6
Sum 1 to 100
Brain TeasersJane StreetGoldman Sachs
72%Easy97
Nim GameLeetCode
Algorithms & NumericalJane StreetSIG / Susquehanna
Easy148
Triangular FX Arbitrage
Market Making & GamesFlow TradersIMC Trading
68%Easy27
Two Dice Sum to 7
ProbabilityOptiverIMC Trading
85%Easy108
Futures Fair Value
FinanceGoldman SachsOptiver
63%Easy169
Information Ratio
Portfolio & RiskBlackRockMillennium Management
76%Easy
5
Day 5

Coding · Brain teasers · Calculus

175
Variance of a Sum
StatisticsGoldman SachsMorgan Stanley
63%Easy68
Geometric Series
Calculus & Linear AlgebraGoldman Sachs
86%Easy124
Most Negative Put Delta
Options & GreeksGoldman SachsOptiver
66%Easy47
Gambler’s Ruin
Stochastic ProcessesJane StreetSIG / Susquehanna
72%Medium79
Product of Array Except SelfLeetCode
Algorithms & NumericalTwo SigmaHRT
Medium9
Last Digit of 2^100
Brain TeasersGoldman SachsMorgan Stanley
60%Easy32
Two Children
ProbabilityGoldman SachsMorgan Stanley
66%Easy
6
Day 6

Coding · Calculus · Finance

150
Piano Tuners in Chicago
Market Making & GamesOptiverIMC Trading
65%Easy109
Duration & Price Sensitivity
FinanceGoldman SachsJ.P. MorganPIMCO
72%Easy170
Beta of a Portfolio
Portfolio & RiskJ.P. MorganBlackRock
76%Easy176
Central Limit Theorem
StatisticsGoldman SachsMorgan Stanley
74%Easy81
Kth Largest ElementLeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium69
Limit of (1+1/n)^n
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
55%Easy126
Sign & Peak of Vega
Options & GreeksOptiverIMC Trading
74%Easy
7
Day 7

Probability · Coding · Brain teasers

50
Covariance of Brownian Motion
Stochastic ProcessesGoldman SachsTwo Sigma
65%Medium38
Expected Rolls for a Six
ProbabilityOptiverIMC Trading
79%Easy13
Handshakes at a Party
Brain TeasersGoldman Sachs
67%Easy83
Maximum Subarray (Kadane)LeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium151
Skewing Off an Inventory
Market Making & GamesOptiverFlow Traders
76%Easy39
At Least One Six
ProbabilitySIG / SusquehannaOptiver
60%Easy110
Perpetuity Value
FinanceGoldman SachsJ.P. Morgan
61%Easy
8
Day 8

Coding · Brain teasers · Calculus

171
Sortino Ratio
Portfolio & RiskMan GroupMillennium Management
76%Easy177
MLE of a Coin
StatisticsTwo SigmaDE Shaw
85%Easy3
Two Eggs, 100 Floors
Brain TeasersGoogleGoldman Sachs
31%Medium71
L'Hôpital — (eˣ−1)/x
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
84%Easy127
Delta Hedging
Options & GreeksOptiverCitadel Securities
76%Easy52
Random Walk Recurrence
Stochastic ProcessesTwo SigmaDE Shaw
69%Medium84
Random Pick with WeightLeetCode
Algorithms & NumericalCitadelTwo Sigma
Medium
9
Day 9

Brain teasers · Finance · Mkt making

23
Roll Until All Six Faces
ProbabilityGoogleTwo Sigma
41%Medium153
The House Edge in European Roulette
Market Making & GamesSIG / SusquehannaFive Rings
52%Easy111
Rule of 72
FinanceGoldman SachsMorgan Stanley
71%Easy156
Two-Asset Portfolio Volatility
Portfolio & RiskGoldman SachsAQR Capital
44%Medium179
Range of Correlation
StatisticsGoldman SachsCitadel
85%Easy4
Horse Race — Top 3
Brain TeasersGoogleTwo Sigma
42%Medium
10
Day 10

Coding · Calculus · Mkt making

85
Shuffle an Array (Fisher-Yates)LeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium24
Birthday Problem
ProbabilityGoldman SachsCitadel
52%Medium72
Derivative of ln(x)
Calculus & Linear AlgebraGoldman Sachs
85%Easy130
How Dear Can a Call Be?
Options & GreeksJane StreetAkuna Capital
76%Easy53
Quadratic Variation of BM
Stochastic ProcessesGoldman SachsTwo Sigma
66%Medium138
Fair Value of a Loaded Die
Market Making & GamesOptiverIMC Trading
68%Medium
11
Day 11

Coding · Brain teasers · Finance

86
Best Time to Buy and Sell StockLeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium7
100 Lockers
Brain TeasersGoogleTwo Sigma
62%Medium26
Drunk Passenger
ProbabilityJane StreetCitadel
55%Medium114
Coupon Equals Yield
FinanceGoldman SachsPIMCO
64%Easy157
Value at Risk (Normal)
Portfolio & RiskGoldman SachsMorgan StanleyMillennium Management
54%Medium180
Variance of a Scaled Variable
StatisticsGoldman Sachs
84%Easy
12
Day 12

Coding · Calculus · Mkt making

89
Rand10() from Rand7()LeetCode
Algorithms & NumericalJane StreetOptiver
Medium73
Sum of First 10 Squares
Calculus & Linear AlgebraJane StreetTwo Sigma
87%Easy132
Find the Put from Parity
Options & GreeksGoldman SachsMorgan Stanley
58%Easy57
Hitting 3 Before 0
Stochastic ProcessesCitadelMorgan Stanley
77%Medium139
Roll, Keep or Re-roll
Market Making & GamesJane StreetSIG / Susquehanna
45%Medium28
Bayes — Disease Test
ProbabilityGoldman SachsTwo Sigma
55%Medium
13
Day 13

Coding · Brain teasers · Finance

8
Poisoned Wine
Brain TeasersGoogleJane Street
35%Medium115
Current Yield
FinanceBarclaysMorgan Stanley
64%Easy158
CVaR / Expected Shortfall
Portfolio & RiskAQR CapitalTwo Sigma
52%Medium183
Width of a 95% Confidence Interval
StatisticsGoldman SachsBlackRock
45%Easy90
Coin Change (DP)LeetCode
Algorithms & NumericalGoogleDE Shaw
Medium29
Broken Stick Triangle
ProbabilityJane StreetCitadel
43%Medium
14
Day 14

Coding · Brain teasers · Calculus

74
Trace = Sum of Eigenvalues
Calculus & Linear AlgebraTwo SigmaGoldman Sachs
82%Easy133
Delta of a Deep ITM Call
Options & GreeksIMC TradingOptiver
74%Easy58
Two Poisson Streams
Stochastic ProcessesJump TradingHRT
70%Medium141
Two Bookmakers, One Arbitrage
Market Making & GamesSIG / SusquehannaFlow Traders
55%Medium10
Mislabeled Jars
Brain TeasersJane StreetOptiver
59%Medium92
Online Stock SpanLeetCode
Algorithms & NumericalCitadel SecuritiesHRT
Medium
15
Day 15

Coding · Brain teasers · Finance

118
Duration and a Rate Move
FinancePIMCOBlackRock
49%Easy159
Diversification & Sharpe
Portfolio & RiskAQR CapitalCitadel
52%Medium30
Top Two Aces
ProbabilitySIG / SusquehannaOptiver
63%Medium184
From Correlation to R²
StatisticsTwo SigmaAQR Capital
60%Easy93
Time-Based Key-Value StoreLeetCode
Algorithms & NumericalTwo SigmaJump Trading
Medium11
Burning Ropes — 45 Minutes
Brain TeasersGoldman SachsMorgan Stanley
76%Medium
16
Day 16

Coding · Calculus · Mkt making

142
The Bookmaker’s Edge
Market Making & GamesSIG / SusquehannaDRW
54%Medium75
Determinant = Product of Eigenvalues
Calculus & Linear AlgebraTwo SigmaDE Shaw
71%Easy135
Straddle Breakeven
Options & GreeksSIG / SusquehannaAkuna Capital
74%Easy59
How Long Until Ruin or Riches
Stochastic ProcessesOptiverSIG / Susquehanna
57%Medium31
Hat Check
ProbabilityJane StreetDE Shaw
72%Medium94
Best Time to Buy and Sell Stock IILeetCode
Algorithms & NumericalOptiverJane Street
Medium
17
Day 17

Brain teasers · Finance · Mkt making

120
Real Rate of Return
FinancePIMCOCitadel
62%Easy160
Maximum Drawdown
Portfolio & RiskCitadelTwo SigmaMan Group
52%Medium187
A One-Sample z-Statistic
StatisticsMorgan StanleyGoldman Sachs
75%Easy14
Bridge Crossing
Brain TeasersGoogleJane Street
49%Medium33
Expected Max of Two Dice
ProbabilityOptiverIMC Trading
41%Medium145
Kelly with 2-to-1 Odds
Market Making & GamesSIG / SusquehannaDRW
40%Medium
18
Day 18

Coding · Calculus · Finance

77
Approximate cos(0.1)
Calculus & Linear AlgebraJane StreetOptiver
84%Easy136
Covered Call Max Profit
Options & GreeksMorgan StanleyIMC Trading
72%Easy60
Half-Life of Mean Reversion
Stochastic ProcessesAQR CapitalMillennium Management
64%Medium95
Gas StationLeetCode
Algorithms & NumericalJane StreetCitadel
Medium105
Black-Scholes ATM Call
FinanceGoldman SachsMorgan Stanley
72%Medium161
Kelly Criterion
Portfolio & RiskCitadelJane Street
59%Medium
19
Day 19

Coding · Brain teasers · Calculus

172
Correlation of X and X²
StatisticsTwo SigmaDE Shaw
74%Medium34
Russian Roulette — Spin?
ProbabilityJane StreetCitadel
62%Medium15
Ants on a Triangle
Brain TeasersGoldman SachsOptiver
84%Medium96
Jump GameLeetCode
Algorithms & NumericalGoogleDE Shaw
Medium146
Two-Thirds of the Average
Market Making & GamesJane StreetOptiver
65%Medium64
Eigenvalues of a 2×2
Calculus & Linear AlgebraGoldman SachsCitadel
80%Medium
20
Day 20

Coding · Brain teasers · Finance

123
Gamma Near Expiry
Options & GreeksOptiverIMC Trading
66%Medium48
Expectation of GBM
Stochastic ProcessesGoldman SachsMorgan Stanley
59%Hard35
Expected Min of Two Dice
ProbabilityOptiverSIG / Susquehanna
71%Medium98
Predict the WinnerLeetCode
Algorithms & NumericalJane StreetOptiver
Medium16
Water Jugs
Brain TeasersGoogle
74%Medium106
Risk-Neutral Probability
FinanceGoldman SachsJ.P. Morgan
81%Medium
21
Day 21

Coding · Calculus · Mkt making

162
VaR Time Scaling
Portfolio & RiskGoldman SachsMorgan Stanley
52%Medium178
Covariance of a Linear Transform
StatisticsGoldman SachsAQR Capital
74%Medium149
The St. Petersburg Game
Market Making & GamesJane StreetTwo Sigma
62%Medium36
Poisson — No Arrivals
ProbabilityTwo SigmaJump Trading
69%Medium99
LRU CacheLeetCode
Algorithms & NumericalTwo SigmaHRT
Medium65
Gaussian Integral
Calculus & Linear AlgebraGoldman SachsTwo Sigma
43%Medium
22
Day 22

Brain teasers · Finance · Options

125
Sign of Theta
Options & GreeksOptiverSIG / Susquehanna
71%Medium51
Expected Flips for HTH
Stochastic ProcessesJane StreetSIG / Susquehanna
45%Hard17
Three Switches
Brain TeasersGoldman SachsMorgan Stanley
70%Medium112
Gordon Growth Model
FinanceGoldman SachsMorgan Stanley
62%Medium163
Minimum-Variance Weight
Portfolio & RiskAQR CapitalBlackRock
52%Medium181
Variance of the Sample Mean
StatisticsTwo SigmaDE Shaw
63%Medium
23
Day 23

Probability · Coding · Brain teasers

37
Exponential Survival
ProbabilityDE ShawMorgan Stanley
52%Medium100
Longest Increasing SubsequenceLeetCode
Algorithms & NumericalTwo SigmaDE Shaw
Medium154
The Doubling “System”
Market Making & GamesSIG / SusquehannaFive Rings
59%Medium20
The Mutilated Chessboard
Brain TeasersGoogleHRT
67%Medium40
Expected Max of Two Uniforms
ProbabilityJane StreetCitadel
51%Medium66
Derivative of xˣ
Calculus & Linear AlgebraJane StreetCitadel
83%Medium
24
Day 24

Coding · Finance · Options

128
Early Exercise of a Call
Options & GreeksGoldman SachsMorgan Stanley
71%Medium54
Random Walk — Expected Steps
Stochastic ProcessesJane StreetTwo Sigma
57%Hard102
Course ScheduleLeetCode
Algorithms & NumericalGoogleDE Shaw
Medium113
Implied Forward Rate
FinanceJ.P. MorganBarclays
65%Medium165
Annualizing Sharpe
Portfolio & RiskTwo SigmaAQR Capital
52%Medium182
The German Tank Problem
StatisticsTwo SigmaDE Shaw
69%Medium
25
Day 25

Coding · Brain teasers · Calculus

140
The Red–Black Card Game
Market Making & GamesJane StreetCitadel Securities
39%Hard43
The Shorter Piece
ProbabilityOptiverMorgan Stanley
52%Medium1
Screwy Pirates
Brain TeasersJane StreetOptiver
51%Hard103
Number of IslandsLeetCode
Algorithms & NumericalGoogleTwo Sigma
Medium70
Integral of x·e^(−x)
Calculus & Linear AlgebraGoldman SachsTwo Sigma
74%Medium129
Delta of an ATM Straddle
Options & GreeksOptiverIMC TradingSIG / Susquehanna
73%Medium
26
Day 26

Finance · Mkt making · Portfolio

55
Expected Running Max of BM
Stochastic ProcessesGoldman SachsDE Shaw
54%Hard116
Forward Price with a Dividend Yield
FinanceJ.P. MorganCitadel
65%Medium166
The Diversification Floor
Portfolio & RiskBlackRockAQR Capital
52%Medium185
Correlation of X with X + Y
StatisticsJane StreetCitadel
57%Medium44
The Secretary Problem
ProbabilityJane StreetDE Shaw
44%Medium144
Quoting Against Informed Flow
Market Making & GamesCitadel SecuritiesSIG / Susquehanna
46%Hard
27
Day 27

Coding · Brain teasers · Calculus

80
Trapping Rain WaterLeetCode
Algorithms & NumericalJane StreetCitadel Securities
Hard12
12 Balls, One Odd
Brain TeasersCitadelJane StreetTwo Sigma
45%Hard45
Galileo’s Three Dice
ProbabilityOptiverIMC Trading
58%Medium82
Sliding Window MaximumLeetCode
Algorithms & NumericalHRTJump Trading
Hard76
Integrate x·eˣ
Calculus & Linear AlgebraGoldman SachsMorgan Stanley
73%Medium131
Value of a Box Spread
Options & GreeksOptiverCitadel Securities
69%Medium
28
Day 28

Brain teasers · Finance · Mkt making

56
The Ballot Problem
Stochastic ProcessesJane StreetDE Shaw
47%Hard117
FX Forward by Interest Parity
FinanceGoldman SachsBarclays
65%Medium167
Minimum-Variance Hedge Ratio
Portfolio & RiskGoldman SachsPIMCO
52%Medium186
Median of an Exponential
StatisticsDE ShawJump Trading
64%Medium147
Shading a First-Price Bid
Market Making & GamesJane StreetDE Shaw
55%Hard18
The Camel and the Bananas
Brain TeasersJane StreetGoogle
40%Hard
29
Day 29

Coding · Calculus · Finance

41
The Tuesday Boy
ProbabilityJane StreetSIG / Susquehanna
44%Hard91
Median of Two Sorted ArraysLeetCode
Algorithms & NumericalGoogleTwo Sigma
Hard67
Maximize x^(1/x)
Calculus & Linear AlgebraJane StreetSIG / Susquehanna
51%Hard134
Worst Case with a Protective Put
Options & GreeksBarclaysJ.P. Morgan
69%Medium61
Reflection Principle for the Maximum
Stochastic ProcessesCitadelDE Shaw
50%Hard119
Present Value of an Annuity
FinanceMorgan StanleyJ.P. Morgan
56%Medium
30
Day 30

Coding · Brain teasers · Mkt making

168
Two-Asset Risk Parity
Portfolio & RiskAQR CapitalMan Group
52%Medium188
Simpson’s Paradox
StatisticsTwo SigmaCitadel
69%Medium152
The Two-Envelope Paradox
Market Making & GamesJane Street
51%Hard19
The Blue-Eyed Islanders
Brain TeasersJane StreetTwo Sigma
40%Hard42
The 100 Prisoners Problem
ProbabilityJane StreetTwo Sigma
45%Hard101
Find Median from Data StreamLeetCode
Algorithms & NumericalTwo SigmaCitadel
Hard