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class User {
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constructor(rank, old, uid = 0) {
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this.rank = rank;
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this.old = old;
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this.seed = 1;
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this.uid = uid;
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}
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}
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class RatingCalculator {
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constructor(users) {
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this.users = [];
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for (const user of users) {
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this.users.push(new User(user.rank, user.old, user.uid));
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}
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}
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// eslint-disable-next-line class-methods-use-this
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calP(a, b) {
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return 1 / (1 + 10 ** ((b.old - a.old) / 400));
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}
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getExSeed(rating, ownUser) {
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const exUser = new User(0.0, rating);
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let result = 1;
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for (const user of this.users) {
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if (user !== ownUser) result += this.calP(user, exUser);
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}
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return result;
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}
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calRating(rank, user) {
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let left = 1;
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let right = 8000;
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while (right - left > 1) {
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const mid = Math.floor((left + right) / 2);
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if (this.getExSeed(mid, user) < rank) right = mid;
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else left = mid;
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}
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return left;
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}
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calculate() {
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// Calculate seed
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for (let i = 0; i < this.users.length; i++) {
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this.users[i].seed = 1;
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for (let j = 0; j < this.users.length; j++) {
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if (i !== j) {
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this.users[i].seed += this.calP(this.users[j], this.users[i]);
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}
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}
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}
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// Calculate initial delta and sum_delta
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let sumDelta = 0;
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for (const user of this.users) {
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user.delta = (this.calRating(Math.sqrt(user.rank * user.seed), user) - user.old) / 2;
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sumDelta += user.delta;
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}
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// Calculate first inc
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let inc = Math.floor(-sumDelta / this.users.length) - 1;
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for (const user of this.users) user.delta += inc;
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// Calculate second inc
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this.users = this.users.sort((a, b) => b.old - a.old);
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const s = Math.min(
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this.users.length,
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Math.floor(4 * Math.round(Math.sqrt(this.users.length))),
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);
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let sumS = 0;
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for (let i = 0; i < s; i++) {
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sumS += this.users[i].delta;
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}
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inc = Math.min(Math.max(Math.floor(-sumS / s), -10), 0);
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// Calculate new rating
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for (const user of this.users) {
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user.delta += inc;
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user.new = user.old + user.delta;
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}
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this.users = this.users.sort((a, b) => a.rank - b.rank);
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return this.users;
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}
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}
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function calculate(users) {
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const calculator = new RatingCalculator(users);
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return calculator.calculate();
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}
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module.exports = calculate;
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