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ballot.sol

pragma solidity ^0.4.0;
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) public {
        chairperson = msg.sender;
        voters[chairperson].weight = 1;
        proposals.length = _numProposals;
    }

    /// Give $(toVoter) the right to vote on this ballot.
    /// May only be called by $(chairperson).
    function giveRightToVote(address toVoter) public {
        if (msg.sender != chairperson || voters[toVoter].voted) return;
        voters[toVoter].weight = 1;
    }

    /// Delegate your vote to the voter $(to).
    function delegate(address to) public {
        Voter storage 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 storage delegateTo = voters[to];
        if (delegateTo.voted)
            proposals[delegateTo.vote].voteCount += sender.weight;
        else
            delegateTo.weight += sender.weight;
    }

    /// Give a single vote to proposal $(toProposal).
    function vote(uint8 toProposal) public {
        Voter storage sender = voters[msg.sender];
        if (sender.voted || toProposal >= proposals.length) return;
        sender.voted = true;
        sender.vote = toProposal;
        proposals[toProposal].voteCount += sender.weight;
    }

    function winningProposal() public constant returns (uint8 _winningProposal) {
        uint256 winningVoteCount = 0;
        for (uint8 prop = 0; prop < proposals.length; prop++)
            if (proposals[prop].voteCount > winningVoteCount) {
                winningVoteCount = proposals[prop].voteCount;
                _winningProposal = prop;
            }
    }
}

RealEstateMarket.sol

pragma solidity ^0.4.18;
pragma experimental ABIEncoderV2;

contract RealEstateMarket {
    struct RealEstate {
        uint id;
        string image;
        string description;
        uint256 price;
        address owner;
    }
    RealEstate[] realEstates;
    RealEstate[] realEstatesForSold;
    
    mapping (address => uint) public balances;
    
    function addRealEstate(uint id, address _owner, string image, string description, uint price) {
        RealEstate memory realEstate = RealEstate(id, image, description, price, _owner);
        
        realEstatesForSold.push(realEstate);
        realEstates.push(realEstate);
    }
    
    function getRealEstatesLength() view public returns (uint) {
        return realEstates.length;
        
    }
    
    function getRealEstate(uint id) public returns (string, string, uint, address) {
        return (
            realEstates[id].image, 
            realEstates[id].description, 
            realEstates[id].price, 
            realEstates[id].owner);
    }
    
    function getRealEstateForSold(uint id) public returns (string, string, uint, address) {
        return (
            realEstatesForSold[id].image, 
            realEstatesForSold[id].description, 
            realEstatesForSold[id].price, 
            realEstates[id].owner);
    }
    
    function  buyRealEstate(uint id) payable {
        if(msg.sender.balance < realEstatesForSold[id].price) return;
        if(msg.value < realEstatesForSold[id].price) return;
        
        realEstatesForSold[id].owner.transfer(msg.value);    
        // emit Sent(msg.sender, receiver, amount);
        
        for(uint i = 0; i < realEstates.length; i++) {
            if(realEstates[i].id == realEstatesForSold[id].id) {
                realEstates[i].owner = msg.sender;
                break;
            }
        }
        
        realEstatesForSold[id] = realEstatesForSold[realEstatesForSold.length - 1];
        realEstatesForSold.length--;
    }
}