java 权重随机算法实现
2024-10-11 17:08:20
import java.util.*;
/**
* 权重随机算法实现
* a b c d 对应权重范围 --- [0,1)、[1,3)、[3,6)、[6,10)
*/
public class RandomSF {
private static TreeMap<String, Integer> hm = new TreeMap<>();
public static void main(String[] args) throws Exception {
TreeMap<String, Integer> randomMap = new TreeMap<String, Integer>();
randomMap.put("a", 1);
randomMap.put("b", 2);
randomMap.put("c", 3);
randomMap.put("d", 4);
Integer tmp = 0;
ArrayList<ElementWeight> arr = new ArrayList<ElementWeight>();
for (Map.Entry<String, Integer> entry : randomMap.entrySet()) {
String key = entry.getKey();
Integer value = entry.getValue();
ElementWeight ew = new ElementWeight(key, tmp, tmp + value);
tmp += value;
arr.add(ew);
}
Random random = new Random();
for (int j = 0; j < 100000000; j++) {
int i = random.nextInt(tmp);
String randomStr = binarySearch(arr, i);
countRandomStr(randomStr);
}
for (ElementWeight ew:arr) {
System.out.println(ew.getElement()+"的权重范围:"+"["+ew.getLow()+","+ew.getHigt()+")");
}
System.out.println(hm);
}
// 二分查找实现
public static String binarySearch(ArrayList<ElementWeight> arr, int num) {
int high = arr.size();
int low = 0;
while (high >= low) {
int middle = (high + low) / 2;
ElementWeight ew = arr.get(middle);
if (num >= ew.getLow() && num < ew.getHigt()) {
return ew.getElement();
} else if (num >= ew.getHigt()) {
low = middle + 1;
} else if (num < ew.getLow()) {
high = middle - 1;
}
}
return null;
}
// 权重元素实体类
static class ElementWeight {
private String element;
private Integer low;
private Integer higt;
public ElementWeight(String element, Integer low, Integer higt) {
this.element = element;
this.low = low;
this.higt = higt;
}
public String getElement() {
return element;
}
public Integer getLow() {
return low;
}
public Integer getHigt() {
return higt;
}
}
// 统计随机string的个数
public static void countRandomStr(String str) {
Integer value = hm.get(str);
if (value == null) {
hm.put(str, 1);
} else {
hm.put(str, ++value);
}
}
}
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