day18, example second parallel

day18/lagoon.go

@@ -7,12 +7,13 @@ import (
 	"slices"
 	"strconv"
 	"strings"
+	"sync"
 )
 
 func Run() int {
 	log.Println("hello day 18")
 	log.Println("problem of lagoon bgins")
-	filename := "day18/example"
+	filename := "day18/input"
 	instructions := ReadInstructionas2(filename)
 	h, w := calcHeightWidth(instructions)
 	log.Printf("read %+v instructions", instructions)
@@ -210,8 +211,10 @@ type Cell struct {
 }
 
 type BorderSymbol rune
-// '' always left to right
-const (Vertical BorderSymbol = '|'
+
+// ” always left to right
+const (
+	Vertical BorderSymbol = '|'
 	ToDown   BorderSymbol = '7'
 	ToUp     BorderSymbol = 'J'
 	FromUp   BorderSymbol = 'F'
@@ -225,6 +228,7 @@ type Field struct {
 	MinRow, MaxRow, MinCol, MaxCol int
 	BordersFromLeft                map[int]map[int]BorderSymbol
 }
+
 func (f *Field) confirmCoord(c Coord) {
 	// log.Printf("configming coord %+v", c)
 
@@ -337,7 +341,6 @@ func getTurnAsIfGoingFromLeft(directionFrom, directionTo Direction)  []BorderSym
 		symbol = FromUp
 	}
 
-
 	// panic(fmt.Sprint("got strange from %s to %s", directionFrom.String(), directionTo.String()))
 	return []BorderSymbol{symbol}
 }
@@ -376,14 +379,36 @@ func (f *Field) String() string {
 	s += "\""
 	return s
 }
-func (f *Field) digInsides() (countInside int) {
+func (f *Field) digInsides() (result int) {
+	lineSum := make(chan int)
+
+	var wg sync.WaitGroup
+	rowsCount := f.MaxRow - f.MinRow
+	wg.Add(rowsCount)
+
+	done := make(chan bool)
+
+	go func() {
+		wg.Wait()
+		close(lineSum)
+	}()
+
+	go func() {
+		for rowInternalCount := range lineSum {
+			result += rowInternalCount
+		}
+		close(done)
+	}()
+
 	for row := f.MinRow; row < f.MaxRow; row++ {
+		go func(row int){
 			if row%10000 == 0 {
 				log.Printf("processed rows %d out of %d", row, f.MaxRow)
 			}
 			specialBorders := f.BordersFromLeft[row]
 			if len(specialBorders) == 0 {
-			continue
+				wg.Done()
+				return
 			}
 			type BorderItem struct {
 				border BorderSymbol
@@ -431,7 +456,8 @@ func (f *Field) digInsides() (countInside int) {
 						// 	ToBeDug: true,
 						// }
 					}
-				countInside += diff
+					lineSum <- diff
+					// countInside += diff
 				}
 
 				if specialBorder.border == Vertical {
@@ -440,8 +466,14 @@ func (f *Field) digInsides() (countInside int) {
 
 				prevBorder = specialBorder
 			}
+
+			wg.Done()
+		}(row)
 	}
-	return
+
+	<-done
+
+	return result
 }
 
 // func (f *Field) digInsides() (countInside int) {

day18/notes.org

@@ -34,3 +34,18 @@ day18 result: 952408144115
 
 952408144115
 *** YES.
+*** about 1M for 4 minutes
+** so, my input is ~16M rows
+3.5 seconds per 10k
+** well, maybe i can parallel.
+*** parallel example
+day18 result: 952407566854
+*** and with separate done channel from the summing goroutine
+952408144115
+**** YES
+** and
+2023/12/18 23:35:31 border is 195341588; inside is 148441957805559
+2023/12/18 23:35:31
+
+day18 result: 148442153147147
+* i should have used a formula. maybe then it would taken less than 4 hours