TournamentExpectator.js

(function(){
  const COUNT = 1000000;
  const FINAL = 1;
  const SORT = false;
  let tournament = [
    [
      [
        [
          {name: '村山慈明', rate: 1737},
          {name: '三枚堂達也', rate: 1760},
        ],
        [
          {name: '丸山忠久', rate: 1731},
          {name: '久保利明', rate: 1814},
        ],
      ],
      [
        [
          {name: '渡辺明', rate: 1793},
          {name: '三浦弘行', rate: 1765},
        ],
        [
          {name: '菅井竜也', rate: 1830},
          {name: '広瀬章人', rate: 1774},
        ],
      ],
    ],
    [
      [
        [
          {name: '澤田真吾', rate: 1748},
          {name: '藤井聡太', rate: 1729},
        ],
        [
          {name: '永瀬拓矢', rate: 1854},
          {name: '佐藤天彦', rate: 1810},
        ],
      ],
      [
        [
          {name: '羽生善治', rate: 1824},
          {name: '高見泰地', rate: 1714, defeated: true},
        ],
        [
          {name: '糸谷哲朗', rate: 1810, defeated: true},
          {name: '八代弥', rate: 1665, defeated: true},
        ],
      ],
    ],
  ];
  let winners = {}, ranking = [], output = '', t = JSON.stringify(tournament);
  let fight = function(a, b){
    let defeat = (w, l) => {l.score = 0; winners[l.name] = l; return w;};
    if(a.defeated) return defeat(b, a);
    if(b.defeated) return defeat(a, b);
    let ea = 1 / (1 + Math.pow(10, (b.rate - a.rate) / 400));
    return (Math.random() < ea) ? a : b;
  };
  let round = function(match){
    if(match === null) return;
    switch(match.length){
      case(1):
        if(match[0].length === 2) return round(match[0]);
        return match[0];
      case(2):
        let a = match[0], b = match[1];
        if(a.length) a = round(a);
        if(b.length) b = round(b);
        return fight(a, b);
      default:
        console.log('Tournament error.');
        return null;
    }
  };
  for(let i = 0; i < COUNT; i++){
    let winner;
    for(let a = round(tournament[0]), b = round(tournament[1]), wins = {}, i = 0; i < FINAL; i++){
      winner = fight(a, b);
      wins[winner.name] = wins[winner.name] + 1 || 1;
      if(wins[winner.name] > FINAL/2) break;
    }
    if(!winners[winner.name]) winners[winner.name] = winner;
    winners[winner.name].score = winner.score + 1 || 1;
  }
  Object.keys(winners).forEach((name) => ranking.push(winners[name]));
  if(SORT) ranking.sort((a, b) => b.score - a.score);
  else ranking.sort((a, b) => t.indexOf(a.name) - t.indexOf(b.name));  
  let digits = String(COUNT).length - 1, format = (score) => (' '.repeat(digits) + score).slice(- digits).replace(/(\d)(?=(\d{3})+(?!\d))/g, '$1,');
  ranking.forEach((player) => output += `${format(player.score)}: (${player.rate}) ${player.name}\n`);
  console.log(output);
  return output;
})();