热爱寻宝的Suimu今天发现了一片宝地,宝地里有n个宝箱,第i个宝箱有P(0<P≤1)的概率开出价值为ai的物品,离开时,Suimu可以将所得物品换成球球币,所得球球币数量为所得物品价值之积(若没有获得任何物品则无法兑换球球币),Suimu想知道最终他离开时球球币数量的期望(答案对998244353取模)。 Input 本题含有多组测试数据. 第一行一个整数T(0 < T ≤≤ 1000),代表测试组数 接下来对于每组测试数据: 第一行三个整数n,p,q(0<n≤100000,0<p≤q<998244353,P≡qp(mod998244353) 第二行n个整数a1,a2,…,an,(0≤ai<998244353)代表每个宝箱的价值 题目保证最多只有10组数据n>10000 Output 对于每组测试数据,输出一个整数代表球球币数量的期望。
时间: 2023-03-26 13:02:50 浏览: 81
我可以回答这个问题。这是一个概率问题,可以使用期望值的公式来求解。设E为期望值,则有:
E = Σ(ai * pi)
其中,ai为第i个宝箱的价值,pi为第i个宝箱开出该价值的概率。根据题目给出的概率P和价值ai,可以计算出pi,然后带入公式求解即可。
需要注意的是,由于数据范围较大,需要使用快速幂算法来计算pi和E,并对结果取模。
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帮我写一个寻宝的DNQ算法的python,基于pytorxh的程序
好的,下面是一个基于PyTorch的DQN算法实现,用于寻宝游戏:
```
import random
import numpy as np
import torch
import torch.nn as nn
import torch.optim as optim
class DQN(nn.Module):
def __init__(self, input_size, hidden_size, output_size):
super(DQN, self).__init__()
self.fc1 = nn.Linear(input_size, hidden_size)
self.fc2 = nn.Linear(hidden_size, hidden_size)
self.fc3 = nn.Linear(hidden_size, output_size)
def forward(self, x):
x = torch.relu(self.fc1(x))
x = torch.relu(self.fc2(x))
x = self.fc3(x)
return x
class ReplayBuffer:
def __init__(self, capacity):
self.capacity = capacity
self.buffer = []
self.position = 0
def push(self, state, action, reward, next_state, done):
if len(self.buffer) < self.capacity:
self.buffer.append(None)
self.buffer[self.position] = (state, action, reward, next_state, done)
self.position = (self.position + 1) % self.capacity
def sample(self, batch_size):
batch = random.sample(self.buffer, batch_size)
state, action, reward, next_state, done = map(np.stack, zip(*batch))
return state, action, reward, next_state, done
def __len__(self):
return len(self.buffer)
class Agent:
def __init__(self, env, input_size, hidden_size, output_size, buffer_capacity=10000, batch_size=32, gamma=0.99, eps_start=1.0, eps_end=0.01, eps_decay=0.999):
self.env = env
self.input_size = input_size
self.hidden_size = hidden_size
self.output_size = output_size
self.buffer = ReplayBuffer(buffer_capacity)
self.batch_size = batch_size
self.gamma = gamma
self.eps_start = eps_start
self.eps_end = eps_end
self.eps_decay = eps_decay
self.steps_done = 0
self.policy_net = DQN(input_size, hidden_size, output_size)
self.target_net = DQN(input_size, hidden_size, output_size)
self.target_net.load_state_dict(self.policy_net.state_dict())
self.target_net.eval()
self.optimizer = optim.Adam(self.policy_net.parameters())
self.criterion = nn.MSELoss()
def select_action(self, state):
eps_threshold = self.eps_end + (self.eps_start - self.eps_end) * \
np.exp(-1. * self.steps_done / self.eps_decay)
self.steps_done += 1
if random.random() > eps_threshold:
with torch.no_grad():
state = torch.tensor(state, dtype=torch.float32)
q_values = self.policy_net(state)
action = q_values.max(0)[1].item()
else:
action = self.env.action_space.sample()
return action
def optimize_model(self):
if len(self.buffer) < self.batch_size:
return
state, action, reward, next_state, done = self.buffer.sample(self.batch_size)
state = torch.tensor(state, dtype=torch.float32)
action = torch.tensor(action, dtype=torch.int64).unsqueeze(1)
reward = torch.tensor(reward, dtype=torch.float32).unsqueeze(1)
next_state = torch.tensor(next_state, dtype=torch.float32)
done = torch.tensor(done, dtype=torch.float32).unsqueeze(1)
q_values = self.policy_net(state).gather(1, action)
next_q_values = self.target_net(next_state).max(1)[0].unsqueeze(1)
expected_q_values = reward + (1 - done) * self.gamma * next_q_values
loss = self.criterion(q_values, expected_q_values)
self.optimizer.zero_grad()
loss.backward()
self.optimizer.step()
def train(self, num_episodes):
for episode in range(num_episodes):
state = self.env.reset()
done = False
while not done:
action = self.select_action(state)
next_state, reward, done, _ = self.env.step(action)
self.buffer.push(state, action, reward, next_state, done)
state = next_state
self.optimize_model()
if episode % 10 == 0:
self.target_net.load_state_dict(self.policy_net.state_dict())
env = gym.make('CartPole-v1')
agent = Agent(env, 4, 128, 2)
agent.train(1000)
```
在这个例子中,我们使用了一个简单的神经网络作为Q函数,使用Replay Buffer来存储经验,使用目标网络来稳定训练。在训练过程中,我们采用了epsilon贪心策略来选择动作,使用Adam优化器来更新网络参数,使用均方误差损失函数来计算损失。最后,我们在CartPole-v1环境中进行了1000个episode的训练。