varunchopra · December 3, 2017 07:19
diff --git a/Day 1: Inverse Captcha b/Day 1: Inverse Captcha
 --- Day 1: Inverse Captcha ---

 The night before Christmas, one of Santa's Elves calls you in a panic. "The printer's broken! We can't print the Naughty or Nice List!" By the time you make it to sub-basement 17, there are only a few minutes until midnight. "We have a big problem," she says; "there must be almost fifty bugs in this system, but nothing else can print The List. Stand in this square, quick! There's no time to explain; if you can convince them to pay you in stars, you'll be able to--" She pulls a lever and the world goes blurry.

 When your eyes can focus again, everything seems a lot more pixelated than before. She must have sent you inside the computer! You check the system clock: 25 milliseconds until midnight. With that much time, you should be able to collect all fifty stars by December 25th.

 Collect stars by solving puzzles. Two puzzles will be made available on each day millisecond in the advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants one star. Good luck!

 You're standing in a room with "digitization quarantine" written in LEDs along one wall. The only door is locked, but it includes a small interface. "Restricted Area - Strictly No Digitized Users Allowed."

 It goes on to explain that you may only leave by solving a captcha to prove you're not a human. Apparently, you only get one millisecond to solve the captcha: too fast for a normal human, but it feels like hours to you.

 The captcha requires you to review a sequence of digits (your puzzle input) and find the sum of all digits that match the next digit in the list. The list is circular, so the digit after the last digit is the first digit in the list.

 For example:

 1122 produces a sum of 3 (1 + 2) because the first digit (1) matches the second digit and the third digit (2) matches the fourth digit.
 1111 produces 4 because each digit (all 1) matches the next.
 1234 produces 0 because no digit matches the next.
 91212129 produces 9 because the only digit that matches the next one is the last digit, 9.

 --- Part Two ---

 You notice a progress bar that jumps to 50% completion. Apparently, the door isn't yet satisfied, but it did emit a star as encouragement. The instructions change:

 Now, instead of considering the next digit, it wants you to consider the digit halfway around the circular list. That is, if your list contains 10 items, only include a digit in your sum if the digit 10/2 = 5 steps forward matches it. Fortunately, your list has an even number of elements.

 For example:

 1212 produces 6: the list contains 4 items, and all four digits match the digit 2 items ahead.
 1221 produces 0, because every comparison is between a 1 and a 2.
 123425 produces 4, because both 2s match each other, but no other digit has a match.
 123123 produces 12.
 12131415 produces 4.

 Input:
 31813174349235972159811869755166343882958376474278437681632495222499211488649543755655138842553867246131245462881756862736922925752647341673342756514856663979496747158241792857625471323535183222497949751644488277317173496124473893452425118133645984488759128897146498831373795721661696492622276282881218371273973538163779782435211491196616375135472517935481964439956844536136823757764494967297251545389464472794474447941564778733926532741752757865243946976266426548341889873514383464142659425122786667399143335772174973128383869893325977319651839516694295534146668728822393452626321892357192574444856264721585365164945647254645264693957898373214897848424966266582991272496771159583715456714645585576641458358326521858518319315233857473695712238323787254556597566461188452279853766184333696344395818615215846348586541164194624371353556812548945447432787795489443312941687221314432694115847863129826532628228386894683392352799514942665396273726821936346663485499159141368443782475714679953213388375939519711591262489869326145476958378464652451441434846382474578535468433514121336844727988128998543975147649823215332929623574231738442281161294838499441799996857746549441142859199799125595761724782225452394593514388571187279266291364278184761833324476838939898258225748562345853633364314923186685534864178665214135631494876474186833392929124337161222959459117554238429216916532175247326391321525832362274683763488347654497889261543959591212539851835354335598844669618391876623638137926893582131945361264841733341247646125278489995838369127582438419889922365596554237153412394494932582424222479798382932335239274297663365164912953364777876187522324991837775492621675953397843833247525599771974555545348388871578347332456586949283657613841414576976542343934911424716613479249893113961925713317644349946444271959375981158445151659431844142242547191181944395897963146947935463718145169266129118413523541222444997678726644615185324461293228124456118853885552279849917342474792984425629248492847827653133583215539325866881662159421987315186914769478947389188382383546881622246793781846254253759714573354544997853153798862436887889318646643359555663135476261863
diff --git a/Day 2: Corruption Checksum b/Day 2: Corruption Checksum
 --- Day 2: Corruption Checksum ---

 As you walk through the door, a glowing humanoid shape yells in your direction. "You there! Your state appears to be idle. Come help us repair the corruption in this spreadsheet - if we take another millisecond, we'll have to display an hourglass cursor!"

 The spreadsheet consists of rows of apparently-random numbers. To make sure the recovery process is on the right track, they need you to calculate the spreadsheet's checksum. For each row, determine the difference between the largest value and the smallest value; the checksum is the sum of all of these differences.

 For example, given the following spreadsheet:

 5 1 9 5
 7 5 3
 2 4 6 8
 The first row's largest and smallest values are 9 and 1, and their difference is 8.
 The second row's largest and smallest values are 7 and 3, and their difference is 4.
 The third row's difference is 6.
 In this example, the spreadsheet's checksum would be 8 + 4 + 6 = 18.

 --- Part Two ---

 "Great work; looks like we're on the right track after all. Here's a star for your effort." However, the program seems a little worried. Can programs be worried?

 "Based on what we're seeing, it looks like all the User wanted is some information about the evenly divisible values in the spreadsheet. Unfortunately, none of us are equipped for that kind of calculation - most of us specialize in bitwise operations."

 It sounds like the goal is to find the only two numbers in each row where one evenly divides the other - that is, where the result of the division operation is a whole number. They would like you to find those numbers on each line, divide them, and add up each line's result.

 For example, given the following spreadsheet:

 5 9 2 8
 9 4 7 3
 3 8 6 5
 In the first row, the only two numbers that evenly divide are 8 and 2; the result of this division is 4.
 In the second row, the two numbers are 9 and 3; the result is 3.
 In the third row, the result is 2.
 In this example, the sum of the results would be 4 + 3 + 2 = 9.

 Input:
 3458	3471	163	1299	170	4200	2425	167	3636	4001	4162	115	2859	130	4075	4269
 2777	2712	120	2569	2530	3035	1818	32	491	872	113	92	2526	477	138	1360
 2316	35	168	174	1404	1437	2631	1863	1127	640	1745	171	2391	2587	214	193
 197	2013	551	1661	121	206	203	174	2289	843	732	2117	360	1193	999	2088
 3925	3389	218	1134	220	171	1972	348	3919	3706	494	3577	3320	239	120	2508
 239	947	1029	2024	733	242	217	1781	2904	2156	1500	3100	497	2498	3312	211
 188	3806	3901	261	235	3733	3747	3721	267	3794	3814	3995	3004	915	4062	3400
 918	63	2854	2799	178	176	1037	487	206	157	2212	2539	2816	2501	927	3147
 186	194	307	672	208	351	243	180	619	749	590	745	671	707	334	224
 1854	3180	1345	3421	478	214	198	194	4942	5564	2469	242	5248	5786	5260	4127
 3780	2880	236	330	3227	1252	3540	218	213	458	201	408	3240	249	1968	2066
 1188	696	241	57	151	609	199	765	1078	976	1194	177	238	658	860	1228
 903	612	188	766	196	900	62	869	892	123	226	57	940	168	165	103
 710	3784	83	2087	2582	3941	97	1412	2859	117	3880	411	102	3691	4366	4104
 3178	219	253	1297	3661	1552	8248	678	245	7042	260	581	7350	431	8281	8117
 837	80	95	281	652	822	1028	1295	101	1140	88	452	85	444	649	1247
	--- Day 1: Inverse Captcha ---

	The night before Christmas, one of Santa's Elves calls you in a panic. "The printer's broken! We can't print the Naughty or Nice List!" By the time you make it to sub-basement 17, there are only a few minutes until midnight. "We have a big problem," she says; "there must be almost fifty bugs in this system, but nothing else can print The List. Stand in this square, quick! There's no time to explain; if you can convince them to pay you in stars, you'll be able to--" She pulls a lever and the world goes blurry.

	When your eyes can focus again, everything seems a lot more pixelated than before. She must have sent you inside the computer! You check the system clock: 25 milliseconds until midnight. With that much time, you should be able to collect all fifty stars by December 25th.

	Collect stars by solving puzzles. Two puzzles will be made available on each day millisecond in the advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants one star. Good luck!

	You're standing in a room with "digitization quarantine" written in LEDs along one wall. The only door is locked, but it includes a small interface. "Restricted Area - Strictly No Digitized Users Allowed."

	It goes on to explain that you may only leave by solving a captcha to prove you're not a human. Apparently, you only get one millisecond to solve the captcha: too fast for a normal human, but it feels like hours to you.

	The captcha requires you to review a sequence of digits (your puzzle input) and find the sum of all digits that match the next digit in the list. The list is circular, so the digit after the last digit is the first digit in the list.

	For example:

	1122 produces a sum of 3 (1 + 2) because the first digit (1) matches the second digit and the third digit (2) matches the fourth digit.
	1111 produces 4 because each digit (all 1) matches the next.
	1234 produces 0 because no digit matches the next.
	91212129 produces 9 because the only digit that matches the next one is the last digit, 9.

	--- Part Two ---

	You notice a progress bar that jumps to 50% completion. Apparently, the door isn't yet satisfied, but it did emit a star as encouragement. The instructions change:

	Now, instead of considering the next digit, it wants you to consider the digit halfway around the circular list. That is, if your list contains 10 items, only include a digit in your sum if the digit 10/2 = 5 steps forward matches it. Fortunately, your list has an even number of elements.

	For example:

	1212 produces 6: the list contains 4 items, and all four digits match the digit 2 items ahead.
	1221 produces 0, because every comparison is between a 1 and a 2.
	123425 produces 4, because both 2s match each other, but no other digit has a match.
	123123 produces 12.
	12131415 produces 4.

	Input:
	31813174349235972159811869755166343882958376474278437681632495222499211488649543755655138842553867246131245462881756862736922925752647341673342756514856663979496747158241792857625471323535183222497949751644488277317173496124473893452425118133645984488759128897146498831373795721661696492622276282881218371273973538163779782435211491196616375135472517935481964439956844536136823757764494967297251545389464472794474447941564778733926532741752757865243946976266426548341889873514383464142659425122786667399143335772174973128383869893325977319651839516694295534146668728822393452626321892357192574444856264721585365164945647254645264693957898373214897848424966266582991272496771159583715456714645585576641458358326521858518319315233857473695712238323787254556597566461188452279853766184333696344395818615215846348586541164194624371353556812548945447432787795489443312941687221314432694115847863129826532628228386894683392352799514942665396273726821936346663485499159141368443782475714679953213388375939519711591262489869326145476958378464652451441434846382474578535468433514121336844727988128998543975147649823215332929623574231738442281161294838499441799996857746549441142859199799125595761724782225452394593514388571187279266291364278184761833324476838939898258225748562345853633364314923186685534864178665214135631494876474186833392929124337161222959459117554238429216916532175247326391321525832362274683763488347654497889261543959591212539851835354335598844669618391876623638137926893582131945361264841733341247646125278489995838369127582438419889922365596554237153412394494932582424222479798382932335239274297663365164912953364777876187522324991837775492621675953397843833247525599771974555545348388871578347332456586949283657613841414576976542343934911424716613479249893113961925713317644349946444271959375981158445151659431844142242547191181944395897963146947935463718145169266129118413523541222444997678726644615185324461293228124456118853885552279849917342474792984425629248492847827653133583215539325866881662159421987315186914769478947389188382383546881622246793781846254253759714573354544997853153798862436887889318646643359555663135476261863
	--- Day 2: Corruption Checksum ---

	As you walk through the door, a glowing humanoid shape yells in your direction. "You there! Your state appears to be idle. Come help us repair the corruption in this spreadsheet - if we take another millisecond, we'll have to display an hourglass cursor!"

	The spreadsheet consists of rows of apparently-random numbers. To make sure the recovery process is on the right track, they need you to calculate the spreadsheet's checksum. For each row, determine the difference between the largest value and the smallest value; the checksum is the sum of all of these differences.

	For example, given the following spreadsheet:

	5 1 9 5
	7 5 3
	2 4 6 8
	The first row's largest and smallest values are 9 and 1, and their difference is 8.
	The second row's largest and smallest values are 7 and 3, and their difference is 4.
	The third row's difference is 6.
	In this example, the spreadsheet's checksum would be 8 + 4 + 6 = 18.

	--- Part Two ---

	"Great work; looks like we're on the right track after all. Here's a star for your effort." However, the program seems a little worried. Can programs be worried?

	"Based on what we're seeing, it looks like all the User wanted is some information about the evenly divisible values in the spreadsheet. Unfortunately, none of us are equipped for that kind of calculation - most of us specialize in bitwise operations."

	It sounds like the goal is to find the only two numbers in each row where one evenly divides the other - that is, where the result of the division operation is a whole number. They would like you to find those numbers on each line, divide them, and add up each line's result.

	For example, given the following spreadsheet:

	5 9 2 8
	9 4 7 3
	3 8 6 5
	In the first row, the only two numbers that evenly divide are 8 and 2; the result of this division is 4.
	In the second row, the two numbers are 9 and 3; the result is 3.
	In the third row, the result is 2.
	In this example, the sum of the results would be 4 + 3 + 2 = 9.

	Input:
	3458 3471 163 1299 170 4200 2425 167 3636 4001 4162 115 2859 130 4075 4269
	2777 2712 120 2569 2530 3035 1818 32 491 872 113 92 2526 477 138 1360
	2316 35 168 174 1404 1437 2631 1863 1127 640 1745 171 2391 2587 214 193
	197 2013 551 1661 121 206 203 174 2289 843 732 2117 360 1193 999 2088
	3925 3389 218 1134 220 171 1972 348 3919 3706 494 3577 3320 239 120 2508
	239 947 1029 2024 733 242 217 1781 2904 2156 1500 3100 497 2498 3312 211
	188 3806 3901 261 235 3733 3747 3721 267 3794 3814 3995 3004 915 4062 3400
	918 63 2854 2799 178 176 1037 487 206 157 2212 2539 2816 2501 927 3147
	186 194 307 672 208 351 243 180 619 749 590 745 671 707 334 224
	1854 3180 1345 3421 478 214 198 194 4942 5564 2469 242 5248 5786 5260 4127
	3780 2880 236 330 3227 1252 3540 218 213 458 201 408 3240 249 1968 2066
	1188 696 241 57 151 609 199 765 1078 976 1194 177 238 658 860 1228
	903 612 188 766 196 900 62 869 892 123 226 57 940 168 165 103
	710 3784 83 2087 2582 3941 97 1412 2859 117 3880 411 102 3691 4366 4104
	3178 219 253 1297 3661 1552 8248 678 245 7042 260 581 7350 431 8281 8117
	837 80 95 281 652 822 1028 1295 101 1140 88 452 85 444 649 1247