The Prison Break | Think Like A Coder, Ep 1 — Transcript

Full transcript

1. 0:29Upon emerging from stasis, Ethic is the unfortunate recipient of three surprises.
2. 0:37The first: a prison cell.
3. 0:40The second: complete amnesia.
4. 0:43And the third: a mysterious stranger has gotten stuck
5. 0:47squeezing through the bars on her window.
6. 0:50His name is Hedge, and he has come to help Ethic save the world.
7. 0:56But first they have to break out of jail.
8. 0:59Hedge turns his hand into a lockpick and outlines the challenge ahead.
9. 1:05Each lock in the prison works in the same unusual way.
10. 1:10Inside the keyhole is a red dial that can be rotated to one of 100 positions
11. 1:17numbered 1 through 100.
12. 1:19The key for a given cell spins the dial to the right position,
13. 1:24which, when stopped there, makes it turn green and unlocks the door.
14. 1:28It would be out of the question to steal keys from a guard,
15. 1:33but Hedge has a better idea.
16. 1:36Hedge can carry out Ethic‘s commands.
17. 1:39If Ethic tells him to walk 5 steps forward,
18. 1:42turn right, then walk another 5 steps,
19. 1:46that’s exactly what he’ll do.
20. 1:49Hedge needs specific instructions though.
21. 1:52If Ethic says “pick the lock” or “try every combination”
22. 1:57that would be too vague, but “spin the dial 5 positions forward” would work.
23. 2:03Once out of the cell, they will only have a few moments to crack the lock
24. 2:07for the outer prison door too before the guards catch them.
25. 2:12So what instructions will allow Hedge to efficiently open any door?
26. 2:20Pause now to figure it out for yourself.
27. 2:25Before we explain the solution, here’s a hint.
28. 2:30A key programming concept that can help unlock the door is called a loop.
29. 2:37This can be one or more instructions that Hedge will iterate— or repeat—
30. 2:42a specified number of times,
31. 2:46like “jump up and down 100 times.”
32. 2:50Or an instruction that Hedge will repeat until a condition is met,
33. 2:55such as “keep jumping up and down until it’s 7 o’clock.”
34. 3:00Pause now to figure it out for yourself.
35. 3:06The first thing that’s clear is that you need to find a way for Hedge
36. 3:10to try every combination until one works.
37. 3:14What takes a little more effort is how exactly you do so.
38. 3:18One solution would be to instruct Hedge to try every combination in succession.
39. 3:23Try 1 and check the light.
40. 3:26If it turns green, open the door, and if not, try 2.
41. 3:32If that doesn’t work try 3. All the way up to 100.
42. 3:38But it would be tedious to lay that out in its entirety.
43. 3:41Why write more than 100 lines of code,
44. 3:44when you can do the same thing with just 3?
45. 3:48This is where a loop comes in.
46. 3:50There are a few ways to go about this.
47. 3:53The lock has 100 positions,
48. 3:56so Ethic could say “Check the dial’s color, then spin the dial forward once,
49. 4:02for 100 repetitions.
50. 4:06Remember where the dial turns green, then have Hedge set it back to that number.”
51. 4:13A loop like this, where you specify the number of times it repeats,
52. 4:17is called a “for" loop.
53. 4:20But an even more efficient loop
54. 4:22would have Hedge spin the dial one position at a time until it turns green
55. 4:27and as soon as that happens, have him stop and open the door.
56. 4:31That way if the door unlocks on 1,
57. 4:35he doesn’t need to cycle through all the rest of the numbers.
58. 4:39This is an “until” loop,
59. 4:42because it involves doing an action until a condition is met.
60. 4:47A similar, alternate approach would be to turn the dial while it’s still red,
61. 4:52then stop.
62. 4:54That’s called a “while” loop.
63. 4:58Back to the adventure.
64. 4:59Hedge loops through the combinations, and the cell opens at 41.
65. 5:07Ethic and Hedge wait until the perfect moment in the guards’ rotation
66. 5:10and make a break for it.
67. 5:14Soon, Ethic faces a choice: hide inside a mysterious crystal,
68. 5:19or try to crack the outer door and make a run for it.
69. 5:23Ethic chooses to run.
70. 5:28The second door takes Hedge longer, requiring him to spin all the way to 93.
71. 5:34But he gets it open
72. 5:43and takes the opportunity to explain why he’s rescued Ethic.
73. 5:48The world is in turmoil:
74. 5:50robots have taken over, and only Ethic can set things right.
75. 5:54In order to do so,
76. 5:55they’ll need to collect three powerful artifacts
77. 5:58that are being used for nefarious purposes across the land.
78. 6:01Only then can Ethic return to the world machine— that giant crystal—
79. 6:05to set things right.
80. 6:19Ethic may have escaped the prison…
81. 6:22but what has she gotten herself into?