标签权重评分Java_Java实现的权重算法（按权重展现广告）

基本算法描述如下:

1、每个广告增加权重

2、将所有匹配广告的权重相加sum，

3、以相加结果为随机数的种子，生成1~sum之间的随机数rd

4、.接着遍历所有广告，访问顺序可以随意.将当前节点的权重值加上前面访问的各节点权重值得curWt,判断curWt >=  rd,如果条件成立则返回当前节点,如果不是则继续累加下一节点. 直到符合上面的条件,由于rd<=sum 因此一定存在curWt>=rd。

特别介绍：

此算法和广告的顺序无关

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Map;

public class Test {

/**

* @param args

*/

@SuppressWarnings("unchecked")

public static void main(String[] args) {

List arrNodes = new ArrayList();

Node n = new Node(10, "测试1");

arrNodes.add(n);

n = new Node(20, "测试2");

arrNodes.add(n);

n = new Node(30, "测试3");

arrNodes.add(n);

n = new Node(40, "测试4");

arrNodes.add(n);

//Collections.sort(arrNodes, new Node());

Map showMap = null;

int sum = getSum(arrNodes);

int random = 0;

Node kw = null;

for(int k = 0; k < 20; k++) {

showMap = new LinkedHashMap();

for(int i = 0; i < 100; i++) {

random = getRandom(sum);

kw = getKW(arrNodes, random);

if(showMap.containsKey(kw.kw)) {

showMap.put(kw.kw, showMap.get(kw.kw) + 1);

} else {

showMap.put(kw.kw, 1);

}

//System.out.println(i + " " +random + " " + getKW(arrNodes, random));

}

System.out.print(k + " ");

System.out.println(showMap);

}

}

public static Node getKW(List nodes, int rd) {

Node ret = null;

int curWt = 0;

for(Node n : nodes){

curWt += n.weight;

if(curWt >= rd) {

ret = n;

break;

}

}

return ret;

}

public static int getSum(List nodes) {

int sum = 0;

for(Node n : nodes)

sum += n.weight;

return sum;

}

public static int getRandom(int seed) {

return (int)Math.round(Math.random() * seed);

}

}

class Node implements Comparator{

int weight = 0;

String kw = "";

public Node() {}

public Node(int wt, String kw) {

this.weight = wt;

this.kw = kw;

}

public String toString(){

StringBuilder sbBuilder = new StringBuilder();

sbBuilder.append(" weight=").append(weight);

sbBuilder.append(" kw").append(kw);

return sbBuilder.toString();

}

public int compare(Object o1, Object o2) {

Node n1 = (Node)o1;

Node n2 = (Node)o2;

if(n1.weight > n2.weight)

return 1;

else

return 0;

}

}