President Elector

Prize Pool TO BE FILLED OUT BY CYFRIN

• Starts: September 12, 2024 Noon UTC

• Ends: September 19, 2024 Noon UTC

• nSLOC: 140

About the Project

With a US election coming up, we started thinking about elections and how... well they suck. Most governments follow a "1 person 1 vote" style voting, which ultimately leads to a 2 party system. So, for our project, we decided to implement a ranked choice on-chain voting mechanism!

Our project showcases a ranked choice voting smart contract. The contract will have a specific set of voters initialized at construction, so we don't have to worry about sybil attacks.

The setup looks as such:

1. The initial president is set as the msg.sender, and each president should have a term of roughly 4 years (1460 days).
2. Voters can call rankCandidates to rank candidates (which can be any address) any time to queue up their votes for the next president.
3. After the 4 year term has passed, anyone can call selectPresident which will select the new s_currentPresident based on the queued up ranks of each voter.
4. Voters can also sign an un-sent transaction so others can spend the gas to cast their vote with rankCandidatesBySig

About Ranked Choice Voting

Ranked choice voting is where candidates rank their choices, as opposed to voting for a single candidate. Once all votes have been collected, candidates go through "rounds" to choose a new president. Each "round" the candidate with the least votes is eliminated, and voters who selected that candidate who was removed will have their vote then count for whoever was selected next. You can see a gif of it here.

Gif from ballotpedia

Actors

• Voters: Users who can vote for president. They are identified at construction time.
• Candidates: Users who received at least 1 vote.
• President: The current winner of the ranked choice algorithm.

Getting Started

Requirements

• git
  • You'll know you did it right if you can run git --version and you see a response like git version x.x.x
• foundry
  • You'll know you did it right if you can run forge --version and you see a response like forge 0.2.0 (816e00b 2023-03-16T00:05:26.396218Z)
• soldeer
  • You'll know you did it right if you can run soldeer --version and you see a response like soldeer 0.x.x

Installation

This repo uses [https://soldeer.xyz/] for package management. If you haven't installed soldeer, head over to their documentation to get started.

git clone https://github.com/Cyfrin/2024-09-president-elector
cd 2024-09-president-elector
soldeer install
forge build

Quickstart

forge test

Scope

./src/RankedChoice.sol

Compatibilities

• solc_version: "0.8.24"
• Chain(s) to deploy to:
  • ETH Mainnet
• Deployment information:
  • Out of scope
• Tokens:
  • None

Known Issues

• In _selectPresidentRecursive there is an issue where if two candidates are tied, whoever was earlier in the list is dropped. This is known, and we are OK with it.
• There are other issues with this style of voting, like for example, in some cases a candidate who does worse will win. You can see a longer explainer here.
• We know that 1460 days is not exactly 4 years. We are OK with that.