Lottery contract

lottery/.env.example

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+ALCHEMY_API_KEY=
+ROPSTEN_PRIVATE_KEY=

lottery/.gitignore

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+node_modules
+.env
+
+#Hardhat files
+cache
+artifacts

lottery/contracts/Lottery.sol

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+// SPDX-License-Identifier: GPL-3.0
+
+pragma solidity >=0.7.0;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "hardhat/console.sol";
+
+contract Lottery is Ownable {
+    uint256 public constant minParticipants = 2;
+    uint256 public constant maxParticipants = 10;
+
+    address payable[] public participants;
+    address payable public lastWinner;
+
+    function participate() external payable {
+        require(msg.value == 0.1 ether, "ticket cost is 0.1 eth"); // 0.1 eth
+        require(
+            participants.length < maxParticipants,
+            "max participants reached for this round"
+        );
+
+        participants.push(payable(msg.sender));
+    }
+
+    function execute() external onlyOwner {
+        require(
+            participants.length >= minParticipants,
+            "need more participants"
+        );
+
+        uint256 randomNumber = uint256(keccak256(abi.encode(block.timestamp)));
+        uint256 winnerIndex = randomNumber % participants.length;
+        lastWinner = participants[winnerIndex];
+        lastWinner.transfer(address(this).balance);
+        delete participants;
+    }
+
+    function participantsCount() external view returns (uint256) {
+        return participants.length;
+    }
+}

lottery/hardhat.config.ts

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+import { task } from "hardhat/config";
+import "@nomiclabs/hardhat-waffle";
+
+import dotenv from 'dotenv'
+dotenv.config()
+
+// This is a sample Hardhat task. To learn how to create your own go to
+// https://hardhat.org/guides/create-task.html
+task("accounts", "Prints the list of accounts", async (args, hre) => {
+  const accounts = await hre.ethers.getSigners();
+
+  for (const account of accounts) {
+    console.log(await account.address);
+  }
+});
+
+// You need to export an object to set up your config
+// Go to https://hardhat.org/config/ to learn more
+
+export default {
+  solidity: "0.8.7",
+  networks: {
+    ropsten: {
+      url: `https://eth-ropsten.alchemyapi.io/v2/${process.env.ALCHEMY_API_KEY}`,
+      accounts: [`0x${process.env.ROPSTEN_PRIVATE_KEY}`],
+    },
+  },
+};