contract Ballot {
struct Voter {
uint weight;
bool voted;
uint8 vote;
address delegate;
}
struct Proposal {
uint voteCount;
}
address chairperson;
mapping(address => Voter) voters;
Proposal[] proposals;
// Create a new ballot with $(_numProposals) different proposals.
function Ballot(uint8 _numProposals) {
chairperson = msg.sender;
voters[chairperson].weight = 1;
proposals.length = _numProposals;
}
// Give $(voter) the right to vote on this ballot.
// May only be called by $(chairperson).
function giveRightToVote(address voter) {
if (msg.sender != chairperson || voters[voter].voted) return;
voters[voter].weight = 1;
}
// Delegate your vote to the voter $(to).
function delegate(address to) {
Voter sender = voters[msg.sender]; // assigns reference
if (sender.voted) return;
while (voters[to].delegate != address(0) && voters[to].delegate != msg.sender)
to = voters[to].delegate;
if (to == msg.sender) return;
sender.voted = true;
sender.delegate = to;
Voter delegate = voters[to];
if (delegate.voted)
proposals[delegate.vote].voteCount += sender.weight;
else
delegate.weight += sender.weight;
}
// Give a single vote to proposal $(proposal).
function vote(uint8 proposal) {
Voter sender = voters[msg.sender];
if (sender.voted || proposal >= proposals.length) return;
sender.voted = true;
sender.vote = proposal;
proposals[proposal].voteCount += sender.weight;
}
function winningProposal() constant returns (uint8 winningProposal) {
uint256 winningVoteCount = 0;
for (uint8 proposal = 0; proposal < proposals.length; proposal++) {
if (proposals[proposal].voteCount > winningVoteCount) {
winningVoteCount = proposals[proposal].voteCount;
winningProposal = proposal;
}
++proposal;
}
}
}
