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  1. import java.util.*;
  2.  
  3. public class Main {
  4.  
  5.     enum Type {
  6.         Normal(10), Rare(2), Yoba(1);
  7.  
  8.         int coefficient;
  9.         Type(int coefficient) { this.coefficient = coefficient; }
  10.     }
  11.  
  12.     static class Item {
  13.         String name;
  14.         int weight;
  15.         Type type;
  16.         double expectedProbability;
  17.  
  18.         public Item(String name, int weight, Type type, double expectedProbability) {
  19.             this.name = name;
  20.             this.weight = weight;
  21.             this.type = type;
  22.             this.expectedProbability = expectedProbability;
  23.         }
  24.  
  25.         @Override
  26.         public String toString() { return name; }
  27.     }
  28.  
  29.     static class WeightedItemSelector {
  30.         private final NavigableMap<Integer, Item> map = new TreeMap<>();
  31.         private final Random random = new Random();
  32.         private final int maxRange;
  33.  
  34.         public WeightedItemSelector(Item... items) {
  35.             int currentWeight = 0;
  36.             for (Item item : items) {
  37.                 currentWeight += item.weight * item.type.coefficient;
  38.                 map.put(currentWeight, item);
  39.             }
  40.             maxRange = currentWeight;
  41.         }
  42.  
  43.         public Item getNext() {
  44.             return map.higherEntry(random.nextInt(maxRange)).getValue();
  45.         }
  46.     }
  47.  
  48.  
  49.  
  50.     private static int iterCount = 1000000;
  51.  
  52.     public static void main(String[] args) {
  53.         WeightedItemSelector selector = new WeightedItemSelector(
  54.                 new Item("Шапка пиздоглазия", 5, Type.Normal, 50 / 207d),
  55.                 new Item("Зелье упоротости", 7, Type.Normal, 70 / 207d),
  56.                 new Item("Картонный щит", 6, Type.Normal, 60 / 207d),
  57.                 new Item("Меч-опиздюливатель", 5, Type.Rare, 10 / 207d),
  58.                 new Item("Шлем из мамкиной кастрюли", 8, Type.Rare, 16 / 207d),
  59.                 new Item("Хуй дракона", 1, Type.Yoba, 1 / 207d)
  60.         );
  61.  
  62.         Map<Item, Integer> counters = new HashMap<>();
  63.         for (int i = 0; i < iterCount; i++) {
  64.             counters.compute(selector.getNext(), (k, v) -> v == null ? 1 : v + 1);
  65.         }
  66.  
  67.         counters.entrySet().forEach(e -> System.out.println(String.format("%s: expected %f, actual %f", e.getKey().name, e.getKey().expectedProbability, e.getValue().doubleValue() / iterCount)));
  68.  
  69.     }
  70.  
  71. }
  72.  
Success #stdin #stdout 0.41s 320832KB
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Шлем из мамкиной кастрюли: expected 0.077295, actual 0.077184
Шапка пиздоглазия: expected 0.241546, actual 0.241527
Картонный щит: expected 0.289855, actual 0.290087
Хуй дракона: expected 0.004831, actual 0.004707
Зелье упоротости: expected 0.338164, actual 0.338564
Меч-опиздюливатель: expected 0.048309, actual 0.047931
https://ideone.com/rGJFg5
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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