ICPC Library

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Formulas

• Expected value of geometric distribution (expected number of failed Bernoulli trials before the first success, where $p$ is the probability of a single success):

  • ${1-p}\over p$

• Sum of arithemtic sequence:

  • $n\times{({a_1+a_n})\over{2}}$
  • ${n\over2}\times{[2a_1 + (n-1)\times d]}$
  • Where:
    • $a_1 =$ first term
    • $d =$ common difference
    • $n =$ number of terms in the range