Complete · 60 Days47 / 188
MediumStochastic ProcessesAcceptance 44%
Flips Until Two Heads in a Row
Jane StreetCitadel
What is the expected number of fair-coin flips to get two heads in a row (HH)?
Approach
Track states: 0 heads so far vs. 1 head so far.
A tail always sends you back to the start state.
Answer
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