Add solution for day 3 part 1
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7f5b3c139c
commit
b1ee8e3538
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package main
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import (
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"errors"
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"fmt"
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"io/ioutil"
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"strconv"
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"strings"
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)
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// Direction represents a direction in space
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type Direction byte
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const (
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// DirectionUp represents the up direction
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DirectionUp Direction = 'U'
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// DirectionDown represents the down direction
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DirectionDown = 'D'
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// DirectionLeft represents the left direction
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DirectionLeft = 'L'
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// DirectionRight represents the right direction
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DirectionRight = 'R'
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)
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// Point represents a point in space
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type Point struct {
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x int
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y int
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}
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// PointSet represents a set of points
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type PointSet map[Point]struct{}
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// DistanceTo finds the manhattan distance between p and p2
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func (p Point) DistanceTo(p2 Point) int {
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return abs(p.x-p2.x) + abs(p.y-p2.y)
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}
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// Add adds the components of two points
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func (p Point) Add(p2 Point) Point {
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return Point{
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x: p.x + p2.x,
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y: p.y + p2.y,
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}
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}
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// Intersection finds the intersection between set1 and set2
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func (set PointSet) Intersection(set2 PointSet) PointSet {
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res := make(PointSet)
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for point := range set {
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if _, ok := set2[point]; ok {
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res[point] = struct{}{}
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}
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}
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return res
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}
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func abs(n int) int {
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if n < 0 {
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return n * -1
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}
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return n
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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// makeDeltaPoint makes a point that represents the delta produced by the path component
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func makeDeltaPoint(pathComponent string) (Point, error) {
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direction := Direction(pathComponent[0])
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distance, err := strconv.Atoi(pathComponent[1:])
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if err != nil {
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return Point{}, errors.New("Invalid number in path component")
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}
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switch direction {
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case DirectionUp:
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return Point{x: 0, y: distance}, nil
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case DirectionDown:
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return Point{x: 0, y: -distance}, nil
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case DirectionLeft:
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return Point{x: -distance, y: 0}, nil
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case DirectionRight:
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return Point{x: distance, y: 0}, nil
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default:
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return Point{}, errors.New("Invalid direction in path component")
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}
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}
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// NewPointSetFromPathString makes a point set of all points from the start, along each path
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func NewPointSetFromPathString(path string) (PointSet, error) {
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cursor := Point{0, 0}
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pathComponents := strings.Split(path, ",")
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pointSet := make(PointSet)
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for _, component := range pathComponents {
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deltaPoint, err := makeDeltaPoint(component)
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if err != nil {
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return nil, fmt.Errorf("Could not make delta point: %s", err)
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}
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newCursor := cursor.Add(deltaPoint)
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xStart := min(cursor.x, newCursor.x)
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xEnd := max(cursor.x, newCursor.x)
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for i := xStart; i < xEnd; i++ {
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pointSet[Point{x: i, y: cursor.y}] = struct{}{}
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}
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yStart := min(cursor.y, newCursor.y)
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yEnd := max(cursor.y, newCursor.y)
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for i := yStart; i < yEnd; i++ {
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pointSet[Point{x: cursor.x, y: i}] = struct{}{}
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}
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cursor = newCursor
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}
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return pointSet, nil
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}
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func part1(paths []PointSet) (int, error) {
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intersections := paths[0]
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// Get all points that intersect between the paths
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for _, path := range paths[1:] {
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intersections = intersections.Intersection(path)
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}
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// We don't care about 0,0 as an intersection, as every path starts there.
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delete(intersections, Point{0, 0})
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// this bitshift represents the max int on the system
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minDistance := int(^uint(0) >> 1)
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for point := range intersections {
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distance := point.DistanceTo(Point{0, 0})
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if distance < minDistance {
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minDistance = distance
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}
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}
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return minDistance, nil
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}
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func main() {
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inputContents, err := ioutil.ReadFile("../input.txt")
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if err != nil {
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panic(err)
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}
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trimmedInput := strings.TrimSpace(string(inputContents))
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rawPaths := strings.Split(trimmedInput, "\n")
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paths := make([]PointSet, len(rawPaths))
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for i, rawPath := range rawPaths {
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paths[i], err = NewPointSetFromPathString(rawPath)
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if err != nil {
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panic(err)
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}
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}
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part1Res, err := part1(paths)
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if err != nil {
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panic(err)
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}
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fmt.Println(part1Res)
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}
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@ -0,0 +1,2 @@
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R1000,U371,R195,U136,R804,U805,L450,U211,R768,U768,L548,U354,L736,U431,L152,U658,L670,D262,L277,U136,L290,U939,R501,U550,L931,D839,R335,D492,L25,U80,R878,U355,R653,U186,R423,D485,L793,D259,L739,U679,R508,D269,R432,D761,R97,D461,L675,U958,L58,U348,L719,D271,R144,U849,R384,U72,L84,U493,R947,U30,L356,D442,R327,U646,R825,U718,L329,D173,L949,D345,L971,D830,L93,U506,R245,D376,R322,D105,L604,D60,R298,D959,L165,D423,R180,D527,R956,D944,R785,U641,L794,D182,R975,D719,L166,U974,L224,U243,L666,U706,R796,D600,L856,D913,L988,D993,L259,U351,R487,D424,L335,U910,L437,D180,R621,D3,R878,D188,R254,D393,L727,U829,R352,U958,L327,D158,L854,D17,R143,D454,R889,D265,L345,U784,R35,D129,R77,U117,R951,D980,L866,U646,R242,D603,L562,U727,L496,U328,L380,D504,R644,U803,L530,D546,R328,D373,L489,U454,R74,D908,R366,U94,R604,D482,L573,D27,R943,U497,L782,D267,L391,U49,R528,D58,R155,D529,R227,D998,R558,D891,R224,U843,R512,U34,R92,U404,R752,U946,L338,D880,L513,D28,L856,D444,L187,U532,L187,U669,L306,U259,R287,D442,R478,U576,R702,U336,L305,U701,L754,D277,R760,D863,L717,U196,L221,U101,L334,D156,L961,D810,L67,D716,L457,D44,L505,D724,R716,D660,L36,D338,R54,U424,R730,U18,L65,D133,R149,U374,R356,D989,R519,U593,L444,D270,R328,U167,L748,D797,L434,U751,R444,D71,R158,D530,L630,U147,R909,D994,L957,U521,L644,D579,R673,U191,R935,U237,R600,D321,L671,U961,L884,U378,R534,D46,R275,U845,R571,U245,L507,U273,R995,U408,L14,D799,L955,D534,R579,D94,R705,D391,R469,D381,R620,U162,R907,D826,R824,U167,L734,U922,L484
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L1007,D620,R853,U77,L13,U473,L253,D410,R897,U464,L862,U281,L650,D470,R87,D204,L896,U670,L864,D950,L75,D320,R901,D785,L653,D225,L857,U616,L143,U940,L664,U131,L547,D745,R636,U569,L50,U454,R288,D254,L36,U377,L609,U929,L714,U85,L939,U923,L566,D280,R243,U948,R447,D7,R908,D151,R824,D432,R34,D81,L458,U745,L420,D982,L625,U910,L729,D274,R910,U322,L984,D88,L700,D349,L932,U510,R625,U88,L252,U785,L378,D101,R299,U66,L476,U696,R236,D46,R590,U157,R461,U305,L269,D487,L676,U467,R319,D524,R75,U65,L478,U861,L238,D716,R888,D12,L184,D578,R266,D226,L656,D172,L752,U124,L831,U810,L663,U538,R417,D770,L359,U1,R12,U791,L332,U272,R574,D942,L857,U447,R310,U342,L713,D258,R590,D585,R129,D115,R832,D967,R981,D159,R864,U423,R268,U519,L52,D493,R445,D657,R885,U166,R155,D264,R51,D632,R525,D875,R617,U898,L556,D386,L143,U278,L767,D389,R821,U869,R286,D90,R289,U54,R15,D764,R46,D674,R983,U49,R959,U779,R958,D247,R483,U156,L18,U12,L178,U540,L499,U487,L544,D336,R814,U267,R145,D135,L920,D902,L933,D507,L997,U361,L577,U425,L773,D782,R117,U851,R998,U503,R902,U781,L161,U98,L653,U633,L91,U629,L138,D19,R147,D756,R364,D529,L764,U913,L118,U856,R774,D621,R151,U154,R737,D960,R86,U458,R991,D481,R560,D858,R223,D6,R931,D301,R552,D797,R284,U368,L967,D686,R940,U410,R137,D156,L6,U643,L445,D999,R888,D277,L852,U210,L777,D36,R103,D652,R120,D67,L642,D527,R913,D858,R69,D433,R864,U75,L531,U456,L664,D452,R801,U851,L824,D278,L526,U133,R200,U768,R15,U393,R982,U287,L38,D114,R86,U299,L819,D891,R379,D601,L244
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