gistfile1.js

var db = [];
var maxCount = 573;
var neibourghsCount = 50;

for (var i = 0; i < maxCount; i++) {
  db[i] = {
    name: 'user' + i,
    id: i,
    exp: Math.round(Math.random() * 10000),
    points: Math.round(Math.random() * 100000)
  }
}

var neibourghs = [];
var last = maxCount % neibourghsCount;
var groupCount = (maxCount - last) / neibourghsCount;

for (i = 0; i < groupCount; i++) {
  neibourghs[i] = db.splice(0, neibourghsCount);
}
neibourghs[i - 1] = neibourghs[i - 1].concat(db);

var getUserGroupId = function (userId) {
  for (var i = 0; i < neibourghs.length; i++) {
    for (var j = 0; j < neibourghs[i].length; j++) {
      if (neibourghs[i][j].id == userId) {
        return i;
      }
    }
  }
}

var getWinnersFromGroupByPoints = function (groupId) {
  var first = 0, second = 0, third = 0;
  for (var i = 0; i < neibourghs[groupId].length; i++) {
    if (neibourghs[groupId][i].points >= neibourghs[groupId][first].points) {
      third = second;
      second = first;
      first = i;
      continue;
    }
    if (neibourghs[groupId][i].points >= neibourghs[groupId][second].points) {
      third = second;
      second = i;
      continue;
    }
    if (neibourghs[groupId][i].points >= neibourghs[groupId][third].points) {
      third = i;
    }
  }
  return {
    first: neibourghs[groupId][first],
    second: neibourghs[groupId][second],
    third: neibourghs[groupId][third]
  };
}