lot (1).sol

// SPDX-License-Identifier: MIT
pragma solidity >= 0.5.0 < 0.9.0;
contract lottery
{
    address public manager;
    address payable[] public participants;

constructor()
{
    manager=msg.sender;
}
receive() external payable 
{
    require(msg.value==0.1 ether);
    participants.push(payable(msg.sender));
}
function getBalance() public view returns(uint)
{
    require(msg.sender==manager);
    return address(this).balance;
}
function random() public view returns(uint){
    return uint(keccak256(abi.encodePacked(block.difficulty,block.timestamp,participants.length)));
}
function selectWinner() public {
    require(msg.sender==manager);
    require(participants.length>=3);
    uint r=random();
    address payable winner;
    uint index=r % participants.length;
    winner=participants[index];
    winner.transfer(getBalance());
}

}