solidity blockchain lottry application

solidity lottery application

/SPDX-License-Identifier: GPL-3.0

//State Vairable  required gas fee 09/June/2022

pragma solidity >= 0.5.0 < 0.9.0;

contract Lottary{

    address public manager;

    address payable[] public participents;

    constructor(){

        manager=msg.sender;

    }

    receive()  external payable{

        require (msg.value==1 ether);

        participents.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,participents.length)));

    }

    function selectwinner() public {

    

        require(msg.sender==manager);

        require(participents.length>=3);

        address payable winner;

        uint r=random();

        uint index=r % participents.length;

        winner= participents[index];

       winner.transfer(getbalance());

       participents=new address payable[](0);

    }

}