红包随机算法

最新推荐文章于 2019-06-08 16:07:58 发布

转载最新推荐文章于 2019-06-08 16:07:58 发布 · 151 阅读

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原文链接：https://my.oschina.net/u/1379199/blog/1608707

本文介绍了一种红包金额随机分配的算法实现，通过Java代码详细展示了如何根据总金额和红包数量生成随机金额列表，并确保每个红包金额在指定范围内，同时保持总金额不变。文章还包含了调整红包金额范围和随机化的具体步骤。

public class RedPackUtils {

public static List<Integer> getRandomRedList(int sum, int count) {
	if (sum <= 0 || count <= 0 || count > sum) {
		throw new RunException(ECode.error, "生成随机金额列表方法调用参数不正确 sum:" + sum + ",count:" + count);
	}
	List<Integer> list = new ArrayList<>();
	for (; count >= 1; count--) {
		int money = getRandomMoney(sum, count);
		sum = sum - money;
		list.add(money);
	}
	if (sum != 0 || count != 0) {
		throw new RunException(ECode.error,
				"生成随机金额列表方法调用失败 sum:" + sum + ",count:" + count + ",list.size():" + list.size());
	}
	return list;
}


public static int getRandomMoney(int sum, int count) {
	if (count == 1) {
		return sum;
	}
	Random r = new Random();
	int min = 1;
	int max = sum / count * 2;
	int money = r.nextInt(max);
	money = money <= min ? 100 : money;
	return money;
}


public static List<Integer> getRandomRedList(int totalSum, int totalCount, int min, int max) {
	List<Integer> randomList = getRandomRedList(totalSum, totalCount);
	int sum = 0;
	for (int i = 0; i < randomList.size(); i++) {
		System.out.println("第" + i + "个:" + randomList.get(i));
		sum = sum + randomList.get(i);
	}
	System.out.println("总额：" + sum);
	Collections.reverse(randomList);
	for (int i = 0; i < totalCount; i++) {
		Integer p = randomList.get(i);
		if (p.intValue() < min) {
			int chae = min - p;
			addToMin(min, chae, randomList);
			randomList.set(i, min);
		}
	}
	Collections.sort(randomList);
	for (int i = 0; i < totalCount; i++) {
		Integer p = randomList.get(i);
		if (p.intValue() > max) {
			int chae = p - max;
			subtractToMax(max, chae, randomList);
			randomList.set(i, max);
		}
	}
	Collections.shuffle(randomList);
	sum = 0;
	for (int i = 0; i < randomList.size(); i++) {
		System.out.println("第" + i + "个:" + randomList.get(i));
		sum = sum + randomList.get(i);
	}
	System.out.println("总额：" + sum);
	return randomList;
}

private static void subtractToMax(int max, int chae, List<Integer> randomList) {
	for (int j = 0; j < randomList.size() && chae > 0;) {
		Integer current = randomList.get(j);
		if (current < max) {
			randomList.set(j, current + 1);
			chae--;
		}
		j++;
		if (chae > 0 && j == randomList.size()) {
			j = 0;
		}
	}

}

private static void addToMin(int min, int chae, List<Integer> randomList) {
	// 排续一下
	for (int j = 0; j < randomList.size() && chae > 0;) {
		Integer current = randomList.get(j);
		if (current > min) {
			randomList.set(j, current - 1);
			chae--;
		}
		j++;
		if (chae > 0 && j == randomList.size()) {
			j = 0;
		}
	}

}

public static void main(String[] args) {
	getRandomRedList(10000000, 500, 100, 20000);
}

}

转载于:https://my.oschina.net/u/1379199/blog/1608707