45 lines
1.0 KiB
Java
45 lines
1.0 KiB
Java
/*
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* Copyright (c) 2017 univento.eu - All rights reserved
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* You are not allowed to use, distribute or modify this code
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*/
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package eu.univento.core.api.utils;
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import java.util.NavigableMap;
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import java.util.Random;
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import java.util.TreeMap;
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class RandomCollection<E> {
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private final NavigableMap<Double, E> map = new TreeMap<>();
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private final Random random;
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private double total = 0.0D;
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public RandomCollection() {
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this(new Random());
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}
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private RandomCollection(Random random) {
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this.random = random;
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}
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public void add(double weight, E result) {
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if (weight <= 0.0D) return;
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this.total += weight;
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this.map.put(this.total, result);
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}
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public E next() {
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double value = this.random.nextDouble() * this.total;
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return this.map.ceilingEntry(value).getValue();
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}
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public E random() {
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double value = this.random.nextDouble() * this.total;
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while (this.random.nextBoolean()) {
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value = this.random.nextDouble() * this.total;
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}
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return this.map.ceilingEntry(value).getValue();
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}
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} |