直接上代码

import java.util.Iterator;

import java.util.TreeSet;

public class Hongbao {

private final int[] moneyList;

private final int number;

private final int totalMoney;

private int cur;

public Hongbao(int number, int totalMoney) {

if (number > totalMoney)

throw new IllegalArgumentException("number <= totalMoney");

this.number = number;

this.totalMoney = totalMoney;

moneyList = new int[number + 1];

TreeSet moneySet = new TreeSet<>();

initial(moneySet);

int i = -1;

Iterator iter = moneySet.iterator();

while (iter.hasNext()) {

moneyList[++i] = iter.next();

}

cur = 0;

}

protected void initial(TreeSet moneySet) {

moneySet.add(0);

moneySet.add(totalMoney);

for (int i = 1; i < number; ++i) {

int tempMoney = rand(totalMoney);

while (moneySet.contains(tempMoney)) {

++tempMoney;

tempMoney %= totalMoney;

}

moneySet.add(tempMoney);

}

}

protected int rand(int n) {

return (int)(Math.random() * (n - 1) + 1);

}

public int getOne() {

return moneyList[++cur] - moneyList[cur - 1];

}

}测试代码

public static void main(String[] args) {

int[] arr = new int[20];

for (int i = 0; i < 20; i++)

arr[i] = 0;

for (int j = 0; j < 4000; ++j) {

Hongbao h = new Hongbao(20, 1000);

for (int i = 0; i < 20; ++i)

arr[i] += h.getOne();

}

for (int i = 0; i < 20; i++)

System.out.println(arr[i]);

}我测试的结果

198741

198305

197537

195746

196592

198304

202119

198655

200099

200290

198616

205446

198713

200420

203392

199065

205758

200732

198460

203010