Day 3

2019-12-03 20:39:07 +01:00
parent 3aa60c0700
commit 43e317a598
2 changed files with 103 additions and 0 deletions
--- a/day03/input.txt
+++ b/day03/input.txt
@@ -0,0 +1,2 @@
+R1002,U407,R530,D268,R516,U937,L74,U838,R784,D684,L912,U746,R189,U192,R868,D345,L972,D492,R942,U631,L559,U634,L80,U513,L746,D997,L348,D160,L655,U949,R717,U396,R549,D167,R591,U469,L22,U977,L167,D856,L320,D920,L396,U490,L895,U180,R661,D828,R864,U189,R307,U402,R409,U445,L101,D418,R812,U419,R319,U75,L813,D46,L491,U39,R737,U11,R177,U311,L278,U254,R475,U166,L515,D105,L694,D437,L298,U169,L613,D234,L999,U380,L711,D758,R932,D27,L951,D529,L935,D189,R816,D176,R98,D320,R965,D333,L367,U622,R18,U83,R275,D205,L960,U177,R750,D466,R442,U797,R355,D717,L569,D578,R384,U863,R541,U405,R527,D658,L514,U168,L64,D918,R947,D11,L189,D875,R599,U201,L165,U772,L679,U566,L195,U660,R896,D622,R678,U390,L984,D900,R889,D714,R557,U848,L176,U541,R518,D699,L904,D23,L55,D886,L206,D621,L48,D197,R502,D259,L779,D72,L183,U747,L424,U452,L603,U561,L430,D942,R515,D378,R962,U508,R230,D650,R804,D453,R899,D813,R484,U798,R456,D231,L316,U117,R630,D436,L985,D283,L393,D370,R158,U957,L914,D455,L875,U536,R889,U400,R347,U712,R487,D455,R428,U590,R127,D132,L202,U377,R138,U654,L760,D46,R213,D225,L817,U455,L612,U543,L525,U979,R591,D940,R446,U786,R750,U244,R325,U928,L44,U551,L955,U221,L986,U516,L916,D242,L280,D71,R80,U849,L271,U626,R737,D646,R82,U120,R646,U569,R463,D94,R570,U456,L548,D687,R221,D759,L606,D818,L859,U218,R682,U299,R818,D966,R407,U605,L859,D378,L53,D722,L216,D221,R639,U485,L865,D620,R99,D988,R944,D323,R540,U372,L470,U106,L804,D92,L177,U518,R277,U670,R451,D194,L695,D502,L601,U596,R374,U682,L19,D54,L156
+L1003,U22,R594,D241,L215,D906,R733,D831,L556,U421,L780,D242,R183,U311,R46,D52,R124,D950,L18,U985,R999,D528,R850,U575,L138,D62,L603,U467,R641,U155,L165,D63,L489,U4,R635,D460,L446,D938,R983,U494,L491,D433,L722,U427,L469,U832,L712,U798,R906,U804,R646,U721,R578,D194,L726,U803,L985,D934,R943,U198,R726,U341,R583,U998,L992,D401,L132,D681,L363,U949,L814,D977,R840,D145,L177,D291,L652,D396,R330,D951,L363,U813,R847,D374,R961,D912,R516,D178,R495,U49,R340,D395,R632,D991,R487,D263,R320,D948,R456,D142,L783,D888,R589,D999,L159,U686,R402,D586,L425,U946,R56,D979,L534,U313,R657,D401,L666,D504,R712,D232,L557,D620,R193,D670,L134,D975,R837,D901,R813,U459,L499,U450,L87,U84,L582,U310,R795,D280,L730,D458,L727,D196,R95,U210,R498,U760,R778,U325,R715,U479,R275,U557,L450,D196,L60,U115,R475,D265,L611,D372,R60,U935,L717,U809,L344,D854,L386,U473,R72,U968,L816,U900,R866,U172,R965,U383,R576,D774,R753,U788,L781,D237,L401,U786,R873,U331,R609,D232,L603,U685,L494,U177,L982,D173,L673,U772,L7,U7,R517,U573,R212,D413,L124,D810,L223,U137,L576,U95,R128,U896,L91,U932,L875,U917,R106,U911,L208,D507,L778,D59,L71,D352,R988,U708,L58,D429,L122,U771,L713,D801,R188,U661,R752,D374,R312,D848,L504,D540,R334,U517,R343,D739,L727,D552,L555,U580,L857,U474,R145,U188,L789,U698,R735,U131,L494,U162,L27,D849,L140,D849,R615,U798,R160,U492,R884,U521,L542,D729,R498,D853,R918,U565,R65,U32,L607,U552,L38,D822,L77,U490,L190,D93,L104,U268,R702,D112,L917,D876,L631,D139,L989,U810,R329,U253,L498,D767,L550,U666,L549,U616,R376
--- a/day03/main.nim
+++ b/day03/main.nim
@@ -0,0 +1,101 @@
+import strutils, hashes, sets, sequtils, algorithm
+
+type Point = object
+  x: int
+  y: int
+
+type Intersection = object
+  point: Point
+  steps: int
+
+proc absCmp(x, y: Point): int =
+  ## Compate Points by absolute values (-3, -3) nad (3, 3) are equal
+  if (x.x.abs + x.y.abs) < (y.x.abs + y.y.abs):
+    return -1
+  if (x.x.abs + x.y.abs) == (y.x.abs + y.y.abs):
+    return 0
+  return 1
+
+proc hash(x: Point): Hash =
+  ## Make Points hashable
+  var h: Hash = 0
+  h = h !& hash(x.x)
+  h = h !& hash(x.y)
+  result = !$h
+
+proc hash(x: Intersection): Hash =
+  ## Make Intersections hashable
+  var h: Hash = 0
+  h = h !& hash(x.point)
+  h = h !& hash(x.steps)
+  result = !$h
+
+iterator inDirection(cursor: var Point, op: string): Point {.closure.} =
+  ## Iterate all Points from the current cursor position to the target of the operation
+  let amount = op.substr(1).parseInt
+  case op[0]:   # The directional letter
+    of 'U':
+      for i in cursor.y + 1 .. cursor.y + amount: 
+       yield Point(x: cursor.x, y: i)
+      cursor.y += amount  
+    of 'R':
+      for i in cursor.x + 1 .. cursor.x + amount:
+        yield Point(x: i, y: cursor.y)
+      cursor.x += amount
+    of 'D':        
+      for i in countdown(cursor.y - 1, cursor.y - amount):
+        yield Point(x: cursor.x, y: i)
+      cursor.y -= amount
+    of 'L':
+      for i in countdown(cursor.x - 1, cursor.x - amount):
+        yield Point(x: i, y: cursor.y)
+      cursor.x -= amount
+    else:
+      raise newException(ValueError, "Unrecognized direction")
+
+proc processOp(cursor: var Point, op: string, compareTo: HashSet[Point], matches: var HashSet[Intersection], steps: var int): seq[Point] =
+  for point in cursor.inDirection(op):
+    result.add(point)
+    steps.inc
+    if compareTo.contains(point):
+      matches.incl(Intersection(point: point, steps: steps))
+
+proc tracePath(line: seq[string], compareTo: HashSet[Point], matches: var HashSet[Intersection]): seq[Point] = 
+  ## Moves along the path, given by the line and saves all visited locations.
+  var 
+    cursor = Point(x: 0, y:0)
+    steps = 0
+  for op in line:
+    result.add(cursor.processOp(op, compareTo, matches, steps))
+
+proc findFirstIntersection(matches1, matches2 : HashSet[Intersection]): int =
+  ## Compare two sets of intersections and find the steps, woth need to reach the first intersection
+  result = int.high
+  for inter1 in matches1:
+    for inter2 in matches2:
+      if inter1.point == inter2.point and result >= inter1.steps + inter2.steps:
+        result = inter1.steps + inter2.steps
+  
+
+var file = open("input.txt", fmRead)
+# Assume there are only two wires
+var line1 = file.readLine.split(",")
+var line2 = file.readLine.split(",")
+
+var 
+  compare: HashSet[Point]
+  matches: HashSet[Intersection]
+
+var path1 = line1.tracePath(compare, matches)
+var path2 = line2.tracePath(compare, matches)
+
+var intersections: seq[Point] = path1.toHashSet.intersection(path2.toHashSet).toSeq
+intersections.sort(absCmp)
+let nearest = intersections[0]
+echo "Part 1. Distance to nearest intersection  ->  ", nearest.x.abs + nearest.y.abs
+
+var path1Matches: HashSet[Intersection]
+var path2Matches: HashSet[Intersection]
+discard line1.tracePath(intersections.toHashSet, path1Matches)
+discard line2.tracePath(intersections.toHashSet, path2Matches)
+echo "Part 2. Combined steps of both wires to first intersection  ->  ", findFirstIntersection(path1Matches, path2Matches)