-
Notifications
You must be signed in to change notification settings - Fork 5
/
WeightedRandom.java
48 lines (42 loc) · 1.08 KB
/
WeightedRandom.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
package com.vee.algorithms.others;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
//FIXME Fix the logic
public class WeightedRandom<T> {
public T getRandomItem(List<Item<T>> items) {
int sumOfWeights = items.stream().collect(Collectors.summingInt(i -> i.weight));
int random = new Random().nextInt(sumOfWeights);
int sum = 0;
T data = items.get(0).data;
for (Item<T> item : items) {
if (random < sum) {
break;
}
data = item.data;
sum += item.weight;
}
return data;
}
public static void main(String args[]) {
WeightedRandom<Integer> wr = new WeightedRandom<Integer>();
List<Item<Integer>> list = new ArrayList<>();
IntStream.range(1,6).forEach(i -> list.add(new Item<Integer>(i,i)));
System.out.println(list);
System.out.println(wr.getRandomItem(list));
}
}
class Item<T> {
T data;
int weight;
public Item(T data, int weight) {
this.data = data;
this.weight = weight;
}
@Override
public String toString() {
return data + "" + weight;
}
}