Contract Source Code:

pragma solidity 0.5.17;

contract RikiMorty {
    using SafeMath for uint256;

    // State variables
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 private _totalSupply;

    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowances;

    // Events as per ERC20 standard
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor(
        string memory tokenName,
        string memory tokenSymbol,
        uint8 decimalUnits,
        uint256 initialSupply
    ) public {
        name = tokenName;
        symbol = tokenSymbol;
        decimals = decimalUnits;
        _totalSupply = initialSupply * (10 ** uint256(decimals));
        _balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }

    // Core ERC20 transfer functions
    function transfer(address recipient, uint256 amount) public returns (bool) {
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[msg.sender] = _balances[msg.sender].sub(amount);
        _balances[recipient] = _balances[recipient].add(amount);

        emit Transfer(msg.sender, recipient, amount);
        return true;
    }

    function approve(address spender, uint256 amount) public returns (bool) {
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);

        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount);
        _balances[recipient] = _balances[recipient].add(amount);

        _allowances[sender][msg.sender] = _allowances[sender][msg.sender].sub(amount);

        emit Transfer(sender, recipient, amount);
        return true;
    }
    // Public functions
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

}

// SafeMath library for arithmetic operations
library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        uint256 c = a - b;

        return c;
    }
}