soa-loans.js

const Random = require('random-js').Random;
const TOTAL_SIMULATIONS = 1;
const MAX_PLAYERS = 100000;
const TOTAL_FRIENDS_PER_PLAYER = 0;

const calculateChoices = () => {
  const random = new Random();
  
  const ALL_PLAYERS = Array(MAX_PLAYERS).fill(0).map((x, i) => i);
  const PLAYERS_CHOSEN_COUNT = Array(MAX_PLAYERS).fill(0);
  const LOANS_PER_DAY_PER_PLAYER = 3;
  
  // only 15 are guaranteed to be on your list
  const PLAYERS_VIEWABLE_IN_LIST_LIMIT = 20;
  
  const PLAYER_FRIENDS = [];
  
  const randomNumberBetween = (min, max) => random.integer(min, max);
  
  const randomSliceOfPlayers = (arr, count) => random.sample(arr, count);
  const randomPlayerFromSlice = (arr) => random.sample(arr, 1)[0];
  
  const choosePlayer = (playerId) => {
    PLAYERS_CHOSEN_COUNT[playerId]++;
  };
  
  const makeFriends = () => {
    for(let i = 0; i < MAX_PLAYERS; i++) {
      PLAYER_FRIENDS[i] = {};
    }
  
    if(!TOTAL_FRIENDS_PER_PLAYER) return;
  };

  makeFriends();

  for(let playerId = 0; playerId < MAX_PLAYERS; playerId++) {
    for(let loanNum = 0; loanNum < LOANS_PER_DAY_PER_PLAYER; loanNum++) {
      let chosenPlayer = -1;

      do {
        const visibleList = randomSliceOfPlayers(ALL_PLAYERS, PLAYERS_VIEWABLE_IN_LIST_LIMIT);
        chosenPlayer = randomPlayerFromSlice(visibleList);
      } while(chosenPlayer === playerId);

      choosePlayer(chosenPlayer);
    }
  }

  return PLAYERS_CHOSEN_COUNT;
};

const analyze = (arr) => {
  let total = 0;
  let min = 10000000000;
  let max = -1;

  arr.forEach(val => {
    total += val;
    if(val < min) min = val;
    if(val > max) max = val;
  });

  return { min, max, total, avg: Math.floor(total / arr.length) };
};

const analyzeAnalyses = (arr) => {
  const total = TOTAL_SIMULATIONS;
  let avgMin = 0;
  let avgMax = 0;
  let avgAvg = 0;

  arr.forEach(({ min, max, avg }) => {
    avgMin += min;
    avgMax += max;
    avgAvg += avg;
  });

  return { endMin: Math.floor(avgMin / arr.length), endMax: Math.floor(avgMax / arr.length), total, endAvg: Math.floor(avgAvg / arr.length) };
};

const allAnalyses = [];

for(let simNum = 0; simNum < TOTAL_SIMULATIONS; simNum++) {
  console.log(`Beginning simulation ${simNum + 1}...`);
  const res = calculateChoices();
  const resAnalysis = analyze(res);
  
  allAnalyses.push(resAnalysis);

  if(TOTAL_SIMULATIONS <= 5) {
    console.log(`Choice results`, res, resAnalysis);
  
    console.log();
  }
}

console.log();
console.log('Final results:', analyzeAnalyses(allAnalyses));