day5: parallelized

day5/dayFive.go

@@ -8,6 +8,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
+	"sync"
 )
 
 type Almanach struct {
@@ -113,14 +114,36 @@ func Run() int {
 		seedRanges = append(seedRanges, []int{start, start+seedRangeLen})
 	}
 
+	rangeMins := make(chan int, len(seedRanges))
+	var wg sync.WaitGroup
+
 	mergedSeedRanges := merge(seedRanges)
 	for _, seedRange := range mergedSeedRanges {
-		log.Printf("starting new range %+v. current min is %n", seedRange, result)
+		wg.Add(1)
-		for i := seedRange[0]; i <= seedRange[1]; i++ {
+		go func(seedRange []int) {
-			location := almanach.locationForSeed(i)
+			log.Printf("starting new range %+v. current min is %d", seedRange, result)
-			if location < result {
+			rangeMin := math.MaxInt
-				result = location
+			for i := seedRange[0]; i <= seedRange[1]; i++ {
+				location := almanach.locationForSeed(i)
+				if location < rangeMin {
+					rangeMins<- location
+					rangeMin = location
+				}
 			}
+			wg.Done()
+			return
+		}(seedRange)
+	}
+
+	go func() {
+		wg.Wait()
+		close(rangeMins)
+	}()
+
+	for rangeMin := range rangeMins {
+		log.Printf("processing range min : %d. cur result is %d", rangeMin, result)
+		if rangeMin <= result {
+			result = rangeMin
 		}
 	}