Weighted Raffle Smart Contract

This NEAR smart contract implements a weighted raffle system. Participants can enter the raffle with different weights, giving them proportionally different chances of winning.

Based off the contract from https://github.com/NEAR-DevHub/race-of-sloths/

Contract Overview

The contract consists of two main structures:

1. Contract: Stores the owner of the contract.
2. Participant: Represents a raffle participant with a name and a weight.

The main function weighted_raffle selects winners based on the weights of the participants.

Functions

new(owner: AccountId) -> Self

Initializes the contract with the given owner.

weighted_raffle(participants: Vec<Participant>, winners: u32) -> Vec<String>

Conducts a weighted raffle and returns the names of the winners.

• participants: A list of Participant objects, each with a name and weight.
• winners: The number of winners to select.

How to Use

1. Deploy the contract to a NEAR account.
2. Call the weighted_raffle function with a list of participants and the number of winners.

Example using NEAR CLI:

near call <contract_account_id> weighted_raffle '{"participants": [{"name": "Alice", "weight": 5}, {"name": "Bob", "weight": 3}, {"name": "Charlie", "weight": 2}], "winners": 2}' --accountId <your_account_id>

Replace <contract_account_id> with the account where the contract is deployed, and <your_account_id> with your NEAR account.

Building and Testing

1. Ensure you have Rust and the NEAR CLI installed.
2. Clone this repository.
3. Build the contract:

   cargo build --target wasm32-unknown-unknown --release
   

4. Deploy the contract using NEAR CLI.
5. Run tests:

   cargo test
   

Notes

• The contract uses a random number generator seeded with env::random_seed() for fairness.
• Participants with higher weights have a higher chance of winning.
• The number of winners must not exceed the number of participants.

License

MIT License