First 5 Questions

contracts/DamnValuableNFT.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
+import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Burnable.sol";
+import "@openzeppelin/contracts/access/AccessControl.sol";
+import "@openzeppelin/contracts/utils/Counters.sol";
+
+/**
+  * @title DamnValuableNFT
+  * @author Damn Vulnerable DeFi (https://damnvulnerabledefi.xyz)
+  * @notice Implementation of a mintable and burnable NFT with role-based access controls
+ */
+contract DamnValuableNFT is ERC721, ERC721Burnable, AccessControl {
+    using Counters for Counters.Counter;
+
+    bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
+    Counters.Counter private _tokenIdCounter;
+
+    constructor() ERC721("DamnValuableNFT", "DVNFT") {
+        _setupRole(DEFAULT_ADMIN_ROLE, msg.sender);
+        _setupRole(MINTER_ROLE, msg.sender);
+    }
+
+    function safeMint(address to) public onlyRole(MINTER_ROLE) returns (uint256) {
+        uint256 tokenId = _tokenIdCounter.current();
+        _safeMint(to, tokenId);
+        _tokenIdCounter.increment();
+        return tokenId;
+    }
+
+    function supportsInterface(bytes4 interfaceId)
+        public
+        view
+        override(ERC721, AccessControl)
+        returns (bool)
+    {
+        return super.supportsInterface(interfaceId);
+    }
+}

contracts/DamnValuableToken.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+
+/**
+ * @title DamnValuableToken
+ * @author Damn Vulnerable DeFi (https://damnvulnerabledefi.xyz)
+ */
+contract DamnValuableToken is ERC20 {
+
+    // Decimals are set to 18 by default in `ERC20`
+    constructor() ERC20("DamnValuableToken", "DVT") {
+        _mint(msg.sender, type(uint256).max);
+    }
+}

contracts/DamnValuableTokenSnapshot.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Snapshot.sol";
+
+/**
+ * @title DamnValuableTokenSnapshot
+ * @author Damn Vulnerable DeFi (https://damnvulnerabledefi.xyz)
+ */
+contract DamnValuableTokenSnapshot is ERC20Snapshot {
+
+    uint256 private lastSnapshotId;
+
+    constructor(uint256 initialSupply) ERC20("DamnValuableToken", "DVT") {
+        _mint(msg.sender, initialSupply);
+    }
+
+    function snapshot() public returns (uint256) {
+        lastSnapshotId = _snapshot();
+        return lastSnapshotId;
+    }
+
+    function getBalanceAtLastSnapshot(address account) external view returns (uint256) {
+        return balanceOfAt(account, lastSnapshotId);
+    }
+
+    function getTotalSupplyAtLastSnapshot() external view returns (uint256) {
+        return totalSupplyAt(lastSnapshotId);
+    }
+}