Author: Tony Li, Trung Le, Vivien Yan.

Practice working with linked structures by developing our simple implementation of blockchains.

• Hash class is a wrapper class that wraps up a byte array along with some operations we would like to perform on it.
• Block class contained each node of the blockchain.
• BlockChain is a class of linked structure consisit of all block.
• BlockChaindriver allows us to interact with our BlockChain.

The main method creates a blockchain with the initial dollar amount and then repeatedly:

1. Prints out the contents of the blockchain.
2. Reads in a command from the user.
3. Executes that command, potentially updating the blockchain and reporting back to the user.

valid command include:

• mine: discovers the nonce for a given transaction
• append: appends a new block onto the end of the chain
• remove: removes the last block from the end of the chain
• check: checks that the block chain is valid
• report: reports the balances of Alexis and Blake
• help: prints this list of commands
• quit: quits the program

Acknowlegment: lab on doubliy linked list, eboards, Danny Wen.