day17, example2

day17/clumsyCrucible.go

@@ -11,17 +11,16 @@ import (
 
 func Run() int {
 	fmt.Println("hello from day 17")
-	filename := "day17/input"
+	filename := "day17/example"
 	field := NewField(filename)
 	log.Printf("%+v\n", field)
 
 	field.RunDijkstra()
 
-	end := Coord{field.Height - 1, field.Width - 1}
-	lenToEnd := field.Paths[end].totalLength
+	lenToEnd := field.Paths[field.Finish].totalLength
 	fmt.Println("check visually:")
 	// fmt.Println(field.Paths[end].stringPathSoFar)
-	fmt.Println(field.Paths[end].stringPathSoFar)
+	fmt.Println(field.Paths[field.Finish].stringPathSoFar)
 	return lenToEnd
 }
 
@@ -127,6 +126,24 @@ type PathSegmentEnd struct {
 	done            bool
 }
 
+func (p *PathSegmentEnd) NextDirections2() (next []Direction) {
+	// last steps of 2 is max allowed 3 tiles in row
+	lastSteps := p.lastSteps[p.lastDirection]
+
+	if lastSteps < 4 {
+		return []Direction{p.lastDirection}
+	}
+
+	next = append(next, p.lastDirection.GetPerpendicular()...)
+
+	if lastSteps < 10 {
+		next = append(next, p.lastDirection)
+	}
+
+	log.Printf("getting directions from %+v they are %+v", p, next)
+	return
+}
+
 func (p *PathSegmentEnd) NextDirections() (next []Direction) {
 	next = append(next, p.lastDirection.GetPerpendicular()...)
 
@@ -145,6 +162,7 @@ type Field struct {
 	Costs         [][]int
 	Height, Width int
 	Start         Coord
+	Finish 	      Coord
 }
 
 func NewField(filename string) Field {
@@ -158,13 +176,16 @@ func NewField(filename string) Field {
 	}
 	initialPaths := make(map[Coord]*PathSegmentEnd)
 	initialPaths[Coord{0, 0}] = &startSegment
+	height := len(enterCosts)
+	width := len(enterCosts[0])
 
 	return Field{
 		Paths:  initialPaths,
 		Costs:  enterCosts,
-		Height: len(enterCosts),
-		Width:  len(enterCosts[0]),
+		Height: height,
+		Width:  width,
 		Start:  Coord{0, 0},
+		Finish: Coord{height - 1, width - 1},
 	}
 }
 
@@ -206,9 +227,19 @@ func (f *Field) RunDijkstra() {
 	distancesMap := make(map[string]int, 0)
 
 	startingPath := f.Paths[f.Start]
-	checking = append(checking, *startingPath)
+	anotherStartingPath := PathSegmentEnd{
+		endsAt: Coord{0, 0},
+		totalLength:   0,
+		lastSteps:     make(map[Direction]int),
+		done:          true,
+		lastDirection: Rightward, // fake, need to init direct neighbors also
+		stringPathSoFar: ".",
+	}
+
+	checking = append(checking, *startingPath, anotherStartingPath)
 
 	distancesMap[startingPath.StringKey()] = 0
+	distancesMap[anotherStartingPath.StringKey()] = 0
 
 	for len(checking) > 0 {
 		var currentPath PathSegmentEnd
@@ -220,23 +251,30 @@ func (f *Field) RunDijkstra() {
 			}
 		}
 		currentCoord := currentPath.endsAt
-		directions := currentPath.NextDirections()
+		directions := currentPath.NextDirections2()
+		// fmt.Printf("> one more iteration for %+v ; directions will check %+v\n", currentPath, directions)
 
 		for _, direction := range directions {
 			neighborCoord := currentCoord.applyDirection(direction)
 			if !f.isValid(neighborCoord) {
 				continue // prevent going off the grid
 			}
-			// log.Printf("from %+v will examine in direction %s to %+v", currentCoord, direction, neighborCoord)
-			// neighborPathSoFar, found := f.Paths[neighborCoord]
-			// if !found {
-			// 	neighborPathSoFar = &PathSegmentEnd{
-			// 		totalLength: math.MaxInt,
-			// 	}
-			// 	f.Paths[neighborCoord] = neighborPathSoFar
-			// }
+			// fmt.Printf("from %+v will examine in direction %s to %+v %+v\n", currentCoord, direction, neighborCoord, currentPath)
+			neighborPathSoFar, found := f.Paths[neighborCoord]
+			if !found {
+				neighborPathSoFar = &PathSegmentEnd{
+					totalLength: math.MaxInt,
+				}
+				f.Paths[neighborCoord] = neighborPathSoFar
+			}
 
 			pathIfWeGoFromCurrent := f.continuePathInDirection(currentPath, direction)
+			if pathIfWeGoFromCurrent.endsAt == f.Finish {
+				if pathIfWeGoFromCurrent.lastSteps[pathIfWeGoFromCurrent.lastDirection] < 4 {
+					continue
+				}
+			}
+
 			distFromThatSide, isKnown := distancesMap[pathIfWeGoFromCurrent.StringKey()]
 			if !isKnown {
 				distancesMap[pathIfWeGoFromCurrent.StringKey()] = pathIfWeGoFromCurrent.totalLength

day17/example2

@@ -0,0 +1,5 @@
+111111111111
+999999999991
+999999999991
+999999999991
+999999999991