selfish-miner.ts

const ADVERSARIAL_POWER = 0.49
const BLOCK_LIMIT = 500
const MONTE_CARLO = 10

function simulate() {
  let honestBlocks = 1
  let adversaryHeadStart = 0
  let chainLength = 1

  while (chainLength < BLOCK_LIMIT) {
    if (Math.random() < ADVERSARIAL_POWER) {
      // adversary got a block
      ++adversaryHeadStart
    }
    else {
      // honest got a block
      if (adversaryHeadStart > 0) {
        --adversaryHeadStart
      }
      else {
        ++honestBlocks
      }
      ++chainLength
    }
  }
  return honestBlocks / BLOCK_LIMIT
}

let sumQuality = 0

for (let i = 0; i < MONTE_CARLO; ++i) {
  sumQuality += simulate()
}
console.log(sumQuality / MONTE_CARLO)