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333 lines
6.6 KiB
Markdown
333 lines
6.6 KiB
Markdown
3 years ago
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https://adventofcode.com/2021/day/11
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## \--- Day 11: Dumbo Octopus ---
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You enter a large cavern full of rare bioluminescent [dumbo
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octopuses](https://www.youtube.com/watch?v=eih-VSaS2g0)! They seem to not like
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the Christmas lights on your submarine, so you turn them off for now.
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There are 100 octopuses arranged neatly in a 10 by 10 grid. Each octopus
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slowly gains _energy_ over time and _flashes_ brightly for a moment when its
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energy is full. Although your lights are off, maybe you could navigate through
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the cave without disturbing the octopuses if you could predict when the
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flashes of light will happen.
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Each octopus has an _energy level_ \- your submarine can remotely measure the
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energy level of each octopus (your puzzle input). For example:
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[code]
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5483143223
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2745854711
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5264556173
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6141336146
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6357385478
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4167524645
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2176841721
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6882881134
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4846848554
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5283751526
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[/code]
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The energy level of each octopus is a value between `0` and `9`. Here, the
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top-left octopus has an energy level of `5`, the bottom-right one has an
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energy level of `6`, and so on.
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You can model the energy levels and flashes of light in _steps_. During a
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single step, the following occurs:
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* First, the energy level of each octopus increases by `1`.
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* Then, any octopus with an energy level greater than `9` _flashes_. This increases the energy level of all adjacent octopuses by `1`, including octopuses that are diagonally adjacent. If this causes an octopus to have an energy level greater than `9`, it _also flashes_. This process continues as long as new octopuses keep having their energy level increased beyond `9`. (An octopus can only flash _at most once per step_.)
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* Finally, any octopus that flashed during this step has its energy level set to `0`, as it used all of its energy to flash.
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Adjacent flashes can cause an octopus to flash on a step even if it begins
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that step with very little energy. Consider the middle octopus with `1` energy
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in this situation:
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[code]
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Before any steps:
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11111
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19991
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19191
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19991
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11111
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After step 1:
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34543
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4 _000_ 4
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5 _000_ 5
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4 _000_ 4
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34543
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After step 2:
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45654
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51115
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61116
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51115
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45654
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[/code]
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An octopus is _highlighted_ when it flashed during the given step.
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Here is how the larger example above progresses:
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[code]
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Before any steps:
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5483143223
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2745854711
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5264556173
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6141336146
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6357385478
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4167524645
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2176841721
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6882881134
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4846848554
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5283751526
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After step 1:
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6594254334
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3856965822
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6375667284
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7252447257
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7468496589
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5278635756
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3287952832
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7993992245
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5957959665
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6394862637
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After step 2:
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88 _0_ 7476555
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5 _0_ 89 _0_ 87 _0_ 54
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85978896 _0_ 8
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84857696 _00_
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87 _00_ 9 _0_ 88 _00_
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66 _000_ 88989
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68 _0000_ 5943
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_000000_ 7456
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9 _000000_ 876
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87 _0000_ 6848
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After step 3:
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_00_ 5 _0_ 9 _00_ 866
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85 _00_ 8 _00_ 575
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99 _000000_ 39
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97 _000000_ 41
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9935 _0_ 8 _00_ 63
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77123 _00000_
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791125 _000_ 9
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221113 _0000_
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_0_ 421125 _000_
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_00_ 21119 _000_
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After step 4:
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2263 _0_ 31977
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_0_ 923 _0_ 31697
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_00_ 3222115 _0_
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_00_ 41111163
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_00_ 76191174
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_00_ 53411122
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_00_ 4236112 _0_
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5532241122
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1532247211
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113223 _0_ 211
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After step 5:
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4484144 _000_
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2 _0_ 44144 _000_
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2253333493
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1152333274
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11873 _0_ 3285
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1164633233
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1153472231
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6643352233
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2643358322
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2243341322
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After step 6:
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5595255111
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3155255222
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33644446 _0_ 5
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2263444496
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2298414396
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2275744344
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2264583342
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7754463344
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3754469433
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3354452433
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After step 7:
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67 _0_ 7366222
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4377366333
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4475555827
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34966557 _0_ 9
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35 _00_ 6256 _0_ 9
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35 _0_ 9955566
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3486694453
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8865585555
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486558 _0_ 644
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4465574644
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After step 8:
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7818477333
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5488477444
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5697666949
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46 _0_ 876683 _0_
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473494673 _0_
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474 _00_ 97688
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69 _0000_ 7564
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_000000_ 9666
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8 _00000_ 4755
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68 _0000_ 7755
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After step 9:
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9 _0_ 6 _0000_ 644
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78 _00000_ 976
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69 _000000_ 8 _0_
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584 _00000_ 82
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5858 _0000_ 93
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69624 _00000_
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8 _0_ 2125 _000_ 9
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222113 _000_ 9
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9111128 _0_ 97
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7911119976
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After step 10:
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_0_ 481112976
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_00_ 31112 _00_ 9
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_00_ 411125 _0_ 4
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_00_ 811114 _0_ 6
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_00_ 991113 _0_ 6
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_00_ 93511233
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_0_ 44236113 _0_
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553225235 _0_
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_0_ 53225 _0_ 6 _00_
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_00_ 3224 _0000_
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[/code]
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After step 10, there have been a total of `204` flashes. Fast forwarding, here
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is the same configuration every 10 steps:
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[code]
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After step 20:
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3936556452
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56865568 _0_ 6
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449655569 _0_
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444865558 _0_
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445686557 _0_
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568 _00_ 86577
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7 _00000_ 9896
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_0000000_ 344
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6 _000000_ 364
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46 _0000_ 9543
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After step 30:
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_0_ 643334118
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4253334611
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3374333458
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2225333337
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2229333338
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2276733333
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2754574565
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5544458511
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9444447111
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7944446119
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After step 40:
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6211111981
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_0_ 421111119
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_00_ 42111115
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_000_ 3111115
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_000_ 3111116
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_00_ 65611111
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_0_ 532351111
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3322234597
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2222222976
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2222222762
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After step 50:
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9655556447
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48655568 _0_ 5
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448655569 _0_
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445865558 _0_
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457486557 _0_
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57 _000_ 86566
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6 _00000_ 9887
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8 _000000_ 533
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68 _00000_ 633
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568 _0000_ 538
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After step 60:
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25333342 _00_
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274333464 _0_
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2264333458
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2225333337
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2225333338
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2287833333
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3854573455
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1854458611
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1175447111
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1115446111
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After step 70:
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8211111164
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_0_ 421111166
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_00_ 42111114
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_000_ 4211115
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_0000_ 211116
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_00_ 65611111
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_0_ 532351111
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7322235117
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5722223475
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4572222754
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After step 80:
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1755555697
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59655556 _0_ 9
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448655568 _0_
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445865558 _0_
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457 _0_ 86557 _0_
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57 _000_ 86566
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7 _00000_ 8666
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_0000000_ 99 _0_
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_0000000_ 8 _00_
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_0000000000_
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After step 90:
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7433333522
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2643333522
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2264333458
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2226433337
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2222433338
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2287833333
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2854573333
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4854458333
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3387779333
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3333333333
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After step 100:
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_0_ 397666866
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_0_ 749766918
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_00_ 53976933
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_000_ 4297822
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_000_ 4229892
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_00_ 53222877
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_0_ 532222966
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9322228966
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7922286866
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6789998766
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[/code]
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After 100 steps, there have been a total of `_1656_` flashes.
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Given the starting energy levels of the dumbo octopuses in your cavern,
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simulate 100 steps. _How many total flashes are there after 100 steps?_
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