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  • Upon emerging from stasis, Ethic is the unfortunate recipient of three surprises.

  • The first: a prison cell.

  • The second: complete amnesia.

  • And the third: a mysterious stranger has gotten stuck

  • squeezing through the bars on her window.

  • His name is Hedge, and he has come to help Ethic save the world.

  • But first they have to break out of jail.

  • Hedge turns his hand into a lockpick and outlines the challenge ahead.

  • Each lock in the prison works in the same unusual way.

  • Inside the keyhole is a red dial that can be rotated to one of 100 positions

  • numbered 1 through 100.

  • The key for a given cell spins the dial to the right position,

  • which, when stopped there, makes it turn green and unlocks the door.

  • It would be out of the question to steal keys from a guard,

  • but Hedge has a better idea.

  • Hedge can carry out Ethic's commands.

  • If Ethic tells him to walk 5 steps forward,

  • turn right, then walk another 5 steps,

  • that's exactly what he'll do.

  • Hedge needs specific instructions though.

  • If Ethic sayspick the lockortry every combination

  • that would be too vague, butspin the dial 5 positions forwardwould work.

  • Once out of the cell, they will only have a few moments to crack the lock

  • for the outer prison door too before the guards catch them.

  • So what instructions will allow Hedge to efficiently open any door?

  • Pause now to figure it out for yourself.

  • Before we explain the solution, here's a hint.

  • A key programming concept that can help unlock the door is called a loop.

  • This can be one or more instructions that Hedge will iterateor repeat

  • a specified number of times,

  • likejump up and down 100 times.”

  • Or an instruction that Hedge will repeat until a condition is met,

  • such askeep jumping up and down until it's 7 o'clock.”

  • Pause now to figure it out for yourself.

  • The first thing that's clear is that you need to find a way for Hedge

  • to try every combination until one works.

  • What takes a little more effort is how exactly you do so.

  • One solution would be to instruct Hedge to try every combination in succession.

  • Try 1 and check the light.

  • If it turns green, open the door, and if not, try 2.

  • If that doesn't work try 3. All the way up to 100.

  • But it would be tedious to lay that out in its entirety.

  • Why write more than 100 lines of code,

  • when you can do the same thing with just 3?

  • This is where a loop comes in.

  • There are a few ways to go about this.

  • The lock has 100 positions,

  • so Ethic could sayCheck the dial's color, then spin the dial forward once,

  • for 100 repetitions.

  • Remember where the dial turns green, then have Hedge set it back to that number.”

  • A loop like this, where you specify the number of times it repeats,

  • is called a “for" loop.

  • But an even more efficient loop

  • would have Hedge spin the dial one position at a time until it turns green

  • and as soon as that happens, have him stop and open the door.

  • That way if the door unlocks on 1,

  • he doesn't need to cycle through all the rest of the numbers.

  • This is anuntilloop,

  • because it involves doing an action until a condition is met.

  • A similar, alternate approach would be to turn the dial while it's still red,

  • then stop.

  • That's called a “whileloop.

  • Back to the adventure.

  • Hedge loops through the combinations, and the cell opens at 41.

  • Ethic and Hedge wait until the perfect moment in the guards' rotation

  • and make a break for it.

  • Soon, Ethic faces a choice: hide inside a mysterious crystal,

  • or try to crack the outer door and make a run for it.

  • Ethic chooses to run.

  • The second door takes Hedge longer, requiring him to spin all the way to 93.

  • But he gets it open

  • and takes the opportunity to explain why he's rescued Ethic.

  • The world is in turmoil:

  • robots have taken over, and only Ethic can set things right.

  • In order to do so,

  • they'll need to collect three powerful artifacts

  • that are being used for nefarious purposes across the land.

  • Only then can Ethic return to the world machinethat giant crystal

  • to set things right.

  • Ethic may have escaped the prison

  • but what has she gotten herself into?

Upon emerging from stasis, Ethic is the unfortunate recipient of three surprises.

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B1 中級 美國腔

越獄|像編碼員一樣思考,第1集。 (The Prison Break | Think Like A Coder, Ep 1)

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    ktyvr258 發佈於 2021 年 01 月 14 日
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