黄金的代码

```python

import hashlib

import json

from time import time

class Block:

def __init__(self, index, transactions, timestamp, previous_hash):

self.index = index

self.transactions = transactions

self.timestamp = timestamp

self.previous_hash = previous_hash

self.hash = self.compute_hash()

def compute_hash(self):

block_string = json.dumps(self.__dict__, sort_keys=True)

return hashlib.sha256(block_string.encode()).hexdigest()

class Blockchain:

def __init__(self):

self.unconfirmed_transactions = []

self.chain = []

self.create_genesis_block()

def create_genesis_block(self):

genesis_block = Block(0, [], time(), "0")

genesis_block.hash = genesis_block.compute_hash()

self.chain.append(genesis_block)

def add_new_transaction(self, transaction):

self.unconfirmed_transactions.append(transaction)

def mine(self):

if not self.unconfirmed_transactions:

return False

last_block = self.chain[-1]

new_block = Block(index=last_block.index + 1,

transactions=self.unconfirmed_transactions,

timestamp=time(),

previous_hash=last_block.hash)

new_block.hash = new_block.compute_hash()

self.chain.append(new_block)

self.unconfirmed_transactions = []

return new_block.index

def is_chain_valid(self):

for i in range(1, len(self.chain)):

current = self.chain[i]

previous = self.chain[i 1]

if current.hash != current.compute_hash():

return False

if current.previous_hash != previous.hash:

return False

return True

创建区块链实例

blockchain = Blockchain()

添加一些交易

blockchain.add_new_transaction("Alice -> Bob -> 10")

blockchain.add_new_transaction("Alice -> Carol -> 5")

挖矿

blockchain.mine()

打印区块链

for block in blockchain.chain:

print(json.dumps(block.__dict__, indent=4))

检查区块链是否有效

print("Blockchain valid?", blockchain.is_chain_valid())

```

这个代码定义了两个类：`Block` 和 `Blockchain`。`Block` 类用于创建一个新的区块，而 `Blockchain` 类用于管理整个区块链。我们创建了一个区块链实例，添加了一些交易，并进行了挖矿。我们打印出区块链的内容，并检查区块链是否有效。

请注意，这只是一个非常基础的区块链实现，用于教学目的。在实际应用中，区块链的实现要复杂得多，并且需要考虑许多安全性和效率方面的因素。