day16, example two

day16/floorWillBeLava.go

@@ -3,6 +3,7 @@ package day16
 import (
 	"fmt"
 	"log"
+	"math"
 	"os"
 	"strings"
 	"sync"
@@ -11,13 +12,63 @@ import (
 func Run() int {
 	fmt.Println("hello from day 16")
 	log.Println("starting")
-	field := ReadField("day16/input")
-	fmt.Println(field.String())
-	field.StartTraversal()
+	filename := "day16/example"
+	field := ReadField(filename)
+	startPoints := StartPoints(&field)
 
-	fmt.Println(field.ShowEnergyzed())
+	var startPointsWaitGroup sync.WaitGroup
+	startPointsWaitGroup.Add(len(startPoints))
 
-	return field.CountEnergized()
+	results := make(chan int)
+
+	go func() {
+		startPointsWaitGroup.Wait()
+		close(results)
+	}()
+
+	for _, start := range startPoints {
+		go func(start MovementPoint) {
+			cleanField := ReadField(filename)
+			cleanField.StartTraversal(start)
+			thisResult := cleanField.CountEnergized()
+			results <- thisResult
+			startPointsWaitGroup.Done()
+		}(start)
+	}
+
+	max := math.MinInt
+	for energized := range results {
+		if energized > max {
+			max = energized
+			log.Println("found new max: ", max)
+		}
+	}
+
+	// fmt.Println(field.String())
+	// field.StartTraversal()
+
+	// fmt.Println(field.ShowEnergyzed())
+
+	return max
+}
+
+func StartPoints(f *Field) []MovementPoint {
+	result := make([]MovementPoint, 0)
+
+	for rowNum, row := range f.cells {
+		result = append(result,
+			MovementPoint{Row: rowNum, Col: 0, Direction: Rightward},
+			MovementPoint{Row: rowNum, Col: len(row) - 1, Direction: Leftward})
+	}
+
+	for colNum, _ := range f.cells[0] {
+		result = append(result,
+			MovementPoint{Row: 0, Col: colNum, Direction: Downward},
+			MovementPoint{Row: len(f.cells) - 1, Col: colNum, Direction: Upward})
+
+	}
+
+	return result
 }
 
 // have shared field
@@ -117,14 +168,11 @@ type MovementPoint struct {
 	Direction Direction
 }
 
-func (f *Field)StartTraversal() {
+func (f *Field) StartTraversal(startPoint MovementPoint) {
 	reportedVisits := make(chan MovementPoint)
 	var wg sync.WaitGroup
 
 	go f.RecordVisits(reportedVisits)
-	startPoint := MovementPoint {
-		Row: 0, Col: 0, Direction: Rightward,
-	}
 	wg.Add(1)
 	go f.TraverseFrom(startPoint, reportedVisits, &wg)