--- Day 1: Historian Hysteria ---
The Chief Historian is always present for the big Christmas sleigh launch, but nobody has seen him in months! Last anyone heard, he was visiting locations that are historically significant to the North Pole; a group of Senior Historians has asked you to accompany them as they check the places they think he was most likely to visit.
As each location is checked, they will mark it on their list with a star. They figure the Chief Historian must be in one of the first fifty places they'll look, so in order to save Christmas, you need to help them get fifty stars on their list before Santa takes off on December 25th.
Collect stars by solving puzzles. Two puzzles will be made available on each day in the Advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants one star. Good luck!
You haven't even left yet and the group of Elvish Senior Historians has already hit a problem: their list of locations to check is currently empty. Eventually, someone decides that the best place to check first would be the Chief Historian's office.
Upon pouring into the office, everyone confirms that the Chief Historian is indeed nowhere to be found. Instead, the Elves discover an assortment of notes and lists of historically significant locations! This seems to be the planning the Chief Historian was doing before he left. Perhaps these notes can be used to determine which locations to search?
Throughout the Chief's office, the historically significant locations are listed not by name but by a unique number called the location ID. To make sure they don't miss anything, The Historians split into two groups, each searching the office and trying to create their own complete list of location IDs.
There's just one problem: by holding the two lists up side by side (your puzzle input), it quickly becomes clear that the lists aren't very similar. Maybe you can help The Historians reconcile their lists?
For example:
3 4
4 3
2 5
1 3
3 9
3 3
Maybe the lists are only off by a small amount! To find out, pair up the numbers and measure how far apart they are. Pair up the smallest number in the left list with the smallest number in the right list, then the second-smallest left number with the second-smallest right number, and so on.
Within each pair, figure out how far apart the two numbers are; you'll need to add up all of those distances. For example, if you pair up a 3 from the left list with a 7 from the right list, the distance apart is 4; if you pair up a 9 with a 3, the distance apart is 6.
In the example list above, the pairs and distances would be as follows:
The smallest number in the left list is 1, and the smallest number in the right list is 3. The distance between them is 2.
The second-smallest number in the left list is 2, and the second-smallest number in the right list is another 3. The distance between them is 1.
The third-smallest number in both lists is 3, so the distance between them is 0.
The next numbers to pair up are 3 and 4, a distance of 1.
The fifth-smallest numbers in each list are 3 and 5, a distance of 2.
Finally, the largest number in the left list is 4, while the largest number in the right list is 9; these are a distance 5 apart.
To find the total distance between the left list and the right list, add up the distances between all of the pairs you found. In the example above, this is 2 + 1 + 0 + 1 + 2 + 5, a total distance of 11!
Your actual left and right lists contain many location IDs. What is the total distance between your lists?
input.txt
63721 98916
83871 23584
55026 62690
21948 69139
11201 33499
96077 62705
41231 87261
71203 13285
53280 86974
31172 11658
56516 98916
59380 19138
96772 61094
63969 69126
20073 82512
20834 38571
92030 96010
84089 39901
18339 22036
28056 25937
75715 99430
70846 98374
56817 62289
97037 22364
32411 51681
41809 98156
76944 37563
58189 69139
21939 82512
45097 86974
62705 26019
95791 61094
31801 84428
69238 88614
39850 13908
26002 39901
64599 33304
44590 98374
78335 51888
82512 52047
57887 78631
27860 51468
72024 12311
47520 51468
97347 59780
13728 65706
52302 74556
33471 98916
14163 40376
20346 83807
80912 17961
95998 65684
32219 24194
46236 13285
98428 88835
40577 61608
91716 98121
60156 70703
54527 51961
42782 12309
42240 83795
15918 50087
42622 14360
22114 99603
87281 54967
91581 99603
52780 23792
46822 82512
30877 29405
33424 11774
32272 82512
78679 62052
36612 29914
42681 61094
48481 52039
69769 62690
64189 40376
54255 66788
54850 66572
12528 22130
86174 40376
65976 80500
63915 28775
66788 83807
83422 66572
90402 99603
85348 80418
14682 98916
45822 28775
13157 20346
38402 31258
80935 10753
65070 20317
32676 34871
31427 15594
42781 47864
55644 44957
30989 42965
38756 62052
39293 97881
30968 62690
56882 29405
65462 68541
76422 50715
34547 24194
72282 62690
92342 42296
25897 20849
14452 82122
75858 15046
75577 85634
20594 77936
39912 68541
69139 31502
64342 61039
71898 31258
53098 20346
39892 37035
10887 98374
97900 94957
67382 97046
10705 40376
68234 89731
51652 54595
51440 62705
97584 97240
21827 63629
96359 84707
15434 61734
93030 97129
56574 67650
24020 67035
23745 68753
40655 66572
97113 16063
81714 15465
27278 54255
36489 66572
30802 98374
26081 72575
61525 18852
82667 66788
73634 90961
64265 61589
21183 62690
77550 68541
29208 12408
54092 85880
40518 54255
89148 50707
50039 64048
38834 73718
62607 75650
15015 78049
97975 29405
92080 42574
83720 22415
93384 69139
40696 44729
97526 23792
61734 92736
38878 98762
20162 77446
77727 69139
27458 18662
36125 20197
75944 18725
86346 22364
44849 75485
65394 60670
39257 34871
17370 35661
61046 66572
73445 78735
23792 95066
33670 28775
31800 69139
37622 60352
34456 98916
82819 39901
36275 77446
71616 33673
14730 28900
62052 60624
55307 34871
75279 74526
89572 31258
66278 27816
84982 57963
99221 19953
86616 56531
31692 98916
51468 24249
48579 38018
52462 97340
80487 28775
99371 35813
70905 66987
39381 33563
62589 23792
24144 83850
16708 29405
43869 28900
39310 53542
85314 15046
95478 28900
61190 98374
21175 82122
13285 72243
99081 70483
10815 39901
93293 86144
95585 98933
65731 50087
99562 23792
93416 66572
49380 22364
95099 29405
94262 62052
50620 98916
16427 34871
18103 13285
17044 86336
35640 61734
27106 34871
99272 28807
68345 44179
47215 14224
99510 34186
59344 66788
56087 23535
54047 80026
18016 63772
72531 71440
59402 40376
92026 34871
56899 79559
45736 36788
43217 91863
77064 98157
56018 20317
76327 28900
72821 19407
63500 62937
68547 66572
42193 37130
81823 22364
72027 82450
59894 57408
22894 26775
49624 34871
85677 13285
59165 28469
15814 98374
18197 93778
48375 14885
94778 98916
86385 97997
41779 73577
52971 34871
91842 61256
22568 61256
14237 54358
76119 55268
54946 28775
71933 65810
86928 24194
10238 98916
80990 69427
28001 39901
47286 32918
70609 66079
15760 36747
36567 94015
11786 34931
18890 78631
46903 39901
50399 74710
89746 66572
31258 50430
49217 99603
71388 98374
65381 63073
26294 20317
97188 98374
36571 22130
68437 35813
40142 31258
51693 29405
29472 67550
85983 99480
83807 38797
36204 40376
22611 40376
66861 24683
86715 62690
24390 12106
78554 74773
16233 91468
46647 17362
18129 98916
74379 24194
39901 94180
28130 89936
15255 53500
90359 98374
36114 24194
69761 78631
40961 96415
32323 35661
72742 53446
18224 51468
79717 66788
63337 62052
83257 77446
70340 20417
37092 23073
11465 91804
93712 51468
70424 20346
79670 47774
53326 99603
61413 35813
28509 77446
10392 51646
20411 79767
10834 34900
46987 77824
84749 14347
64003 60388
37510 23792
67074 15046
86583 22130
74774 17706
27254 32069
24780 62690
74592 66572
19956 50397
87787 78631
27551 86335
27313 62690
11764 13285
16566 68541
52387 43204
32314 30981
50548 23792
66572 98374
23813 14490
10031 73014
98916 99603
85669 51468
41290 31893
79434 77446
41146 75460
21093 31258
22150 39901
77726 76376
86750 35661
52067 34432
22075 52433
80197 29405
43183 40376
48981 51468
49114 65262
17821 83795
66079 72103
61094 54261
22863 86785
79221 35813
37160 86690
43323 60348
27816 98916
23797 13285
52087 83795
69710 62690
37097 62690
58946 35813
25528 78631
95945 39426
10344 83292
25204 22035
20851 44476
49675 18087
60917 98916
38511 66788
50625 13566
92213 42204
14434 35517
16747 79017
98256 82122
13429 23798
10505 22364
56299 51468
11971 98374
82974 95791
71227 93187
17329 20899
86233 48880
64887 13285
67572 72363
42339 16540
37301 88128
99216 13285
21173 13285
39433 80508
56739 98916
19158 66788
99366 97494
78631 76828
64445 49058
84071 27319
76591 94653
72285 39901
86827 68541
97195 50087
94820 39901
51240 66572
19704 13285
82252 54471
90511 81325
39890 82624
28900 23792
89837 29405
27432 20051
12464 68541
51911 49067
70069 51468
38185 96194
61979 61734
44809 34871
50816 74433
88128 62052
68302 11847
65790 14562
18639 61545
43973 50325
32245 71996
32770 78631
80007 24194
81848 17710
48925 27816
36951 78631
44300 83864
39815 88563
33287 87639
81599 40376
83780 34010
76105 37309
66186 57599
30330 15408
85410 76902
32775 62690
96368 35661
36267 31258
63258 50558
29106 28298
82546 62690
11099 61734
78293 25816
96305 15046
29590 35661
62248 69139
28271 78631
28395 61256
64484 97925
25386 35813
27975 55981
62690 55244
36937 36761
14288 78631
58395 15040
71622 20346
29580 10650
19543 29405
91211 62052
67129 23792
71075 89904
35814 78631
24320 66399
68616 62052
81607 13285
16440 69113
20317 34871
34990 86694
46814 17420
48773 18642
16983 12462
76286 22364
43760 50461
89012 98374
76734 83795
82889 81347
94844 83039
87086 42228
79066 34871
60930 62690
14671 98362
15046 98916
23105 64417
15963 26384
17578 66788
19749 35813
73717 77781
55768 78631
81328 86974
98374 30582
74371 98916
62198 66788
18216 29620
83718 35167
97216 66806
21853 23792
95659 45644
54690 19553
99854 54434
60953 82122
29405 20346
77446 61734
74477 61881
59384 34871
22201 82512
41680 22364
70388 33526
79474 35813
95676 61734
81066 86974
50184 69139
92334 73193
63301 74886
88694 25546
29122 40376
35513 61734
34871 51468
27159 78631
92093 22364
97523 46887
75320 75413
50553 66788
69335 39901
31428 36441
63138 38796
65691 66589
18442 61734
95290 40828
30463 84566
13760 20346
63642 38111
38068 99603
88985 51468
86911 13890
81763 98405
60314 34871
79229 98374
54222 37457
41191 35661
94686 14344
48723 40376
53331 51468
82320 32023
13879 64243
77615 78631
21373 81177
99603 28900
74982 17203
61957 82512
49736 29405
71158 16258
46734 68257
91305 13285
15307 77446
88888 75540
96953 82122
73049 34871
25806 66509
28775 22364
88849 84256
73085 31258
82002 45833
92219 61094
94438 62690
74931 10907
19013 56348
61330 51468
45424 32416
85351 51468
43176 78631
92511 31258
74316 50766
52865 80456
90670 19338
60903 50287
13027 23792
70012 37373
28645 95137
29890 52066
90210 22364
83928 91550
84224 95653
52748 22364
25385 89306
29258 61754
22425 81852
83606 23792
86286 33987
78304 78631
46454 77446
68130 78631
84341 34871
32536 98374
46176 51468
18381 52328
74842 12157
99320 34871
36587 51215
65504 11768
62256 20755
62433 28900
18797 64268
46028 56766
34433 39901
55237 69139
67094 83807
59294 29927
18052 66788
37438 65122
89900 22130
86138 66808
17409 61734
41410 77446
36675 98987
93185 40326
68737 97123
12420 28900
28431 13285
79903 61734
85029 49719
87114 38161
10277 97814
91030 77446
60032 40376
26941 71642
40711 62052
66007 98916
36232 22130
77300 66788
82122 74191
93403 86974
10869 26173
32606 39901
36002 90403
37936 61256
36223 14536
90084 98370
13588 29405
92588 23792
76528 68541
91855 98758
65053 77446
31950 15046
20160 83646
98329 13285
59162 20346
78821 86974
73311 15046
83143 14519
61256 47938
68103 43062
62427 72651
50329 77446
93857 91804
50509 31563
12726 98916
91094 51468
62068 97829
88270 51468
98814 42679
96608 66788
21920 22364
85592 59267
56819 39901
60434 69139
68767 20590
23123 31258
64662 78921
26559 45234
72799 82122
83414 62705
35661 22364
22499 53665
90831 52136
31956 56969
53393 20346
30160 91715
40872 68541
96530 20724
73972 46762
23784 77789
51604 14275
24516 33815
51694 36170
54999 40276
71340 77446
33559 50566
97770 86974
57181 98916
11456 95791
43991 35813
39647 99603
31291 48238
24411 66572
50087 15046
36907 81744
84965 43494
80699 26639
70287 28114
30928 62052
29829 27652
45493 29405
96002 68340
86510 83248
58569 14674
95602 83044
60548 62973
87844 29873
64650 24194
91993 61256
25193 12039
93597 69445
44397 75998
16429 68541
36998 98916
46382 35813
73943 56489
18980 38254
52184 29113
27861 53315
78208 52158
39137 95325
71411 96871
11297 50795
24795 10762
45672 85223
20458 45112
68342 86974
48555 68541
14057 89657
45348 83795
69091 85340
32017 91553
47365 29405
69846 42783
42794 66079
55767 35661
79443 18679
97731 28900
78728 46714
51662 61502
86974 40376
66784 69988
21713 26696
67541 89573
63234 48739
75844 11283
72169 63197
68116 27816
39756 58055
49060 52912
86033 20346
77374 32945
54054 15032
10242 66300
39964 39901
16823 98374
35949 64043
45790 71364
85734 62690
39953 67342
19397 36827
30706 47034
62392 27816
36736 76359
41284 27040
91564 18615
27419 49560
35658 83795
88035 27816
58920 61094
24194 53105
41569 61734
88977 67702
59178 31337
91804 24194
68538 51029
45699 22539
64646 39901
49570 66788
42702 66572
10875 16521
54579 34871
30993 82512
46568 99603
36007 61734
41554 40376
28737 86974
47642 54509
95772 28900
91043 31258
84273 98374
75931 71232
40158 35777
40376 95791
52356 68460
63119 77046
85547 24461
48564 15619
61344 14922
20517 68541
69816 52014
33687 82149
39886 57790
85582 77421
16170 48400
32839 24194
59842 14809
40767 22364
14572 86974
94812 29405
29781 20317
25093 51468
22523 15286
69772 49833
24511 89853
95422 63827
18619 62557
71465 56921
80392 23792
75031 22130
88990 61046
62453 63513
10363 61094
33426 40376
34338 98916
19106 22364
16632 21897
93602 80485
70657 83807
87290 93753
48905 69139
19137 58766
74790 78631
17479 66515
59784 40376
35921 69139
63281 99603
49035 54255
42278 49216
88656 61094
18166 68541
15171 27816
25018 66572
58709 66788
26678 52650
51627 82122
71638 28900
52703 93929
54658 29405
63402 77446
62250 36480
20727 96945
66177 13629
11052 95791
16012 70360
14890 58523
68314 61256
27581 61256
68541 66572
96645 99603
79922 66079
45897 37920
46727 62690
92327 50087
97244 19990
97604 92430
10996 21728
54944 66788
51431 75661
44593 70853
57290 22130
44100 51468
88066 95791
64545 62690
15185 98374
81005 83795
24581 59570
18803 39901
31017 35731
52752 16550
55973 83795
41888 77446
54026 23792
45685 23792
39267 15380
74192 99479
48209 75402
43467 78806
83468 68541
22364 44940
22179 52910
61634 23792
45998 72739
41096 35813
17074 39901
34245 99603
38149 66572
87211 34871
39320 39901
35813 69139
72525 29405
17308 20346
26336 35661
16331 31258
18176 61256
28796 86974
91989 40376
76266 72180
79522 97407
46148 98374
91891 90085
29539 88770
97919 99153
14625 62052
33094 31225
75423 62690
64206 66079
91522 17031
36889 86974
98905 35912
67253 22364
86480 62690
47746 68541
54727 40171
39202 68929
83795 17632
19065 77446
73523 79097
63938 59651
64774 22364
86179 83795
19996 75565
49609 66760
22417 31817
90246 15046
25158 27060
27237 61256
20154 11191
80548 61256
83429 39901
82411 39901
36646 99815
89469 34241
69714 73572
17832 65920
98578 62023
26264 78372
23951 10088
91003 39552
14615 99603
78726 83194
31384 44477
22130 45848
83121 81284
87043 42282
25669 40376
61080 98374
29216 68226
19808 31190
12025 77446
49018 46070
71086 35813
26776 48041
94075 35661
51192 34871
18698 61094
77232 66079
18652 44005
47380 86974
91250 69139
54224 23792
22462 23279
96949 25734
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76499 35842
13733 89585
47074 51199
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41926 82925
51892 88913
56351 49034
39241 85194
43972 20620
main.test.ts
import { distance, parseLists, part1, part2 } from "./main";
describe("Day 01", () => {
describe("distance", () => {
it('checks distances', () => {
expect(distance(1, 3)).toBe(2);
expect(distance(2, 3)).toBe(1);
expect(distance(3, 3)).toBe(0);
expect(distance(3, 4)).toBe(1);
expect(distance(3, 5)).toBe(2);
expect(distance(4, 9)).toBe(5);
})
})
describe("parseLists", () => {
it('parses lists', () => {
const result = parseLists(`3 4
4 3
2 5
1 3
3 9
3 3`)
const [list1, list2] = result;
expect(list1).toEqual([3, 4, 2, 1, 3, 3])
expect(list2).toEqual([4, 3, 5, 3, 9, 3])
})
})
describe("part1", () => {
it('solves the problem', () => {
const solution = part1(`3 4
4 3
2 5
1 3
3 9
3 3`)
expect(solution).toBe(11);
});
})
describe("part2", () => {
it('solves the problem', () => {
const solution = part2(`3 4
4 3
2 5
1 3
3 9
3 3`)
expect(solution).toBe(31);
});
})
})
main.ts
import { readFileSync } from "fs";
// Generic Utilities
function zip<T>(arr1: T[], arr2: T[]): [T, T][] {
return arr1.map((item, index) => [item, arr2[index]]);
}
function sum(total: number, entry: number): number {
return total + entry
}
function solve<T>(inputFile: string, solution: (input: string) => T): T {
const data = readFileSync(inputFile, "utf-8").trim()
const solved = solution(data)
return solved
}
// Functions for this problem
export function distance(a: number, b: number): number {
return Math.abs(a - b)
}
function parseNumbers(line: string): number[] {
return line.split(/\s+/).map(num => parseInt(num))
}
function buildLists(prevLists: [number[], number[]], numbers: number[]): [number[], number[]] {
const [first, second] = numbers
return [
[...prevLists[0], first],
[...prevLists[1], second]
]
}
export function parseLists(input: string): [number[], number[]] {
return input.trim().split("\n").map(parseNumbers).reduce(buildLists, [[], []])
}
// Solutions
export function part1(input: string): number {
let [list1, list2] = parseLists(input);
list1.sort()
list2.sort()
return zip(list1, list2).map(([a, b]) => distance(a, b)).reduce(sum)
}
// Part 2
function entryCount(value: number, otherList: number[]): number {
return otherList.filter(v => v == value).length
}
export function part2(input: string): number {
let [list1, list2] = parseLists(input);
return list1.map(i => i * entryCount(i, list2)).reduce(sum)
}
console.log("Part 1: ", solve("src/day-01/input.txt", part1)) //?
console.log("Part 2: ", solve("src/day-01/input.txt", part2)) //?