Loaded Die Algorithm in Solidity?

Question

I am trying to implement a smart contract, that takes in a discreet distribution and returns a loaded random number. The higher the number higher the chance from 1-10000.

**anyone has any experience with this or ideas?

Answer 1

Here is an example from "Building Games with Ethereum Smart Contracts".

contract SatoshiDice {
    struct Bet {
    address user;
    uint block;
    uint cap;
    uint amount;
    }

    uint public constant FEE_NUMERATOR = 1;
    uint public constant FEE_DENOMINATOR = 100;
    uint public constant MAXIMUM_CAP = 100000;
    uint public constant MAXIMUM_BET_SIZE = 1e18;
    address owner;
    uint public counter = 0;
    mapping(uint => Bet) public bets;
    event BetPlaced(uint id, address user, uint cap, uint amount);
    event Roll(uint id, uint rolled);

function SatoshiDice () public {
    owner = msg.sender;
    }

function wager (uint cap) public payable {
    require(cap <= MAXIMUM_CAP);
    require(msg.value <= MAXIMUM_BET_SIZE);
    counter++;
    bets[counter] = Bet(msg.sender, block.number + 3, cap,
    msg.value);
    BetPlaced(counter, msg.sender, cap, msg.value);
}

function roll(uint id) public {
    Bet storage bet = bets[id];
    require(msg.sender == bet.user);
    require(block.number >= bet.block);
    require(block.number <= bet.block + 255);
    bytes32 random = keccak256(block.blockhash(bet.block), id);
    uint rolled = uint(random) % MAXIMUM_CAP;
    if (rolled < bet.cap) {
        uint payout = bet.amount * MAXIMUM_CAP / bet.cap;
        uint fee = payout * FEE_NUMERATOR / FEE_DENOMINATOR;
        payout -= fee;
        msg.sender.transfer(payout);
    }

    Roll(id, rolled);
    delete bets[id];
    }
    
    function fund () payable public {}
    function kill () public {
    require(msg.sender == owner);
    selfdestruct(owner);
 }
}

As the explanation for this kind of contracts is beyond a StackExchange answer, I'd recommend reading the book and/or more about random number generation on-chain.