Birthday Prize Simulation

birthday.js

main()

function main() {
    var prizes = [-1, -1, -1, 1, 1, 2, 2, 2, 3, 3, 5, 5, 5, 5, 5, 20, 20, 20, 20, 20, 20, 40, 40, 40, 60, 100];
    var simulationResults = Array.from({ length: prizes.length }, (_, i) => simulateTurns(prizes, i + 1));
    console.log(simulationResults);
}

function simulateTurns(prizes, selectionCount = 15, turns = 10000) {
    let winningsForAllTurns = Array.from({ length: turns }, () => simulateGame(prizes, selectionCount));
    return calculateMean(winningsForAllTurns);
}

function simulateGame(prizes, selectionCount) {
    let maxBusts = [...prizes].filter(num => num === -1).length;
    let shuffledPrizes = shuffleArray(prizes);

    let currentWinnings = 0;
    let minusOneCount = 0;
    
    for (let i = 0; i < selectionCount; i++) {
        const selection = shuffledPrizes[i]
        if (selection === -1) {
            minusOneCount++;
            currentWinnings = 0; // Lose everything if -1 is selected
            if (minusOneCount === maxBusts) {
                // game over
                break;
            }
            continue;
        }
        currentWinnings += selection;
    }

    return currentWinnings
}

function shuffleArray(array) {
  const shuffledArray = [...array];
  for (let i = shuffledArray.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [shuffledArray[i], shuffledArray[j]] = [shuffledArray[j], shuffledArray[i]];
  }
  return shuffledArray;
}

function calculateMean(numbers) {
  if (numbers.length === 0) { return 0; }

  const sum = numbers.reduce((acc, curr) => acc + curr, 0);
  const mean = sum / numbers.length;

  return Math.round(mean); // simplify to whole number
}