PickClass.sol

//Classes
//Record Studuent pick.
//Cal Result 
//Studuent Pick Class(Not Pick)
//Pick End Time.
//Query Time 

pragma solidity ^0.4.8;
import "https://github.com/OpenZeppelin/zeppelin-solidity/contracts/math/SafeMath.sol";
contract PickClass {
    using SafeMath for uint;
    address[] private pickClassStudents;
    address[] private chosedClassStudents;
    mapping(address => bool) chosed;
    mapping(address => bool) picked;
    address owner;
    uint private classMaxStudent = 2;
    uint private currentRandomLength;
    uint private test;
    
    modifier isValidPick() {
        require(!picked[msg.sender]);
        _;
    }
    
    modifier isOwner() {
        require(msg.sender == owner);
        _;
    }
    
    
    
    function PickClass() public {
        owner = msg.sender;
        
        //it's for test 
        pickClassStudents.push(0x0);
        pickClassStudents.push(0x1);
        pickClassStudents.push(0x2);
        pickClassStudents.push(0x3);
        pickClassStudents.push(0x4);
        pickClassStudents.push(0x5);
    }

    function pickClass() isValidPick public {
        pickClassStudents.push(msg.sender);
        picked[msg.sender] = true;
    }
    
    function calClassResult() isOwner public {
        //Random
        currentRandomLength = pickClassStudents.length;
        uint pickStudentsLength = pickClassStudents.length;
        for(int i = 0; i < classMaxStudent; ++i) {
            
        }
        // test = chosedClassStudents.length;
        // while(test < classMaxStudent) {
        //     uint chosedRandom = random(0, currentRandomLength);
        //     chosedClassStudents.push(pickClassStudents[chosedRandom]);
        //     (pickClassStudents[chosedRandom], pickClassStudents[pickStudentsLength]) = (pickClassStudents[pickStudentsLength], pickClassStudents[chosedRandom]);
        //     currentRandomLength.sub(1);
        //     test = chosedClassStudents.length;
        // }
    }
    
    function isChosed() public view returns(bool) {
        return chosed[msg.sender];
    }
    
    function checkResult() public view returns(address[]) {
        return chosedClassStudents;
    }
    
    function checkPickStudent() public view returns(address[]) {
        return pickClassStudents;
    }
    
    function random(uint min, uint max) private constant returns(uint) {
        return now % (max - min) + min;
    }
}