run loop logic in separate goroutines.

use bool channel + waitgroups to collect results

day-04/internal/one/solve.go

@@ -2,6 +2,7 @@ package one
 
 import (
 	"bytes"
+	"sync"
 
 	log "github.com/sirupsen/logrus"
 )
@@ -13,37 +14,53 @@ func Solve(buf []byte) (int, error) {
 		return 0, err
 	}
 
-	var sum int
+	wg := sync.WaitGroup{}
+	sumChan := make(chan bool)
 
 	for i := 0; i < len(graph.data); i++ {
 		for j := 0; j < len(graph.data[i]); j++ {
-			current := newPoint(j, i)
-			if graph.valueAt(current) == 'X' {
-				for _, n := range neighbours(current) {
-					if checkNeighbours(graph, n, "MAS") {
-						sum++
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+
+				current := newPoint(j, i)
+				if graph.valueAt(current) == 'X' {
+					for _, n := range neighbours(current) {
+						sumChan <- checkNeighbours(n, "MAS", graph)
 					}
 				}
-			}
+			}()
+		}
+	}
+
+	go func() {
+		wg.Wait()
+		close(sumChan)
+	}()
+
+	var sum int
+	for val := range sumChan {
+		if val {
+			sum++
 		}
 	}
 
 	return sum, nil
 }
 
-func checkNeighbours(graph *graph, n point, word string) bool {
+func checkNeighbours(n point, word string, g *graph) bool {
 	if len(word) == 0 {
 		log.Debug("we found a full XMAS")
 		return true
 	}
 
-	if graph.isOutOfBounds(n) {
+	if g.isOutOfBounds(n) {
 		return false
 	}
 
-	if graph.valueAt(n) != rune(word[0]) {
+	if g.valueAt(n) != rune(word[0]) {
 		return false
 	}
 
-	return checkNeighbours(graph, neighbours(n)[n.direction], word[1:])
+	return checkNeighbours(neighbours(n)[n.direction], word[1:], g)
 }