feat(2020-24/angch): Faster, using neighbourcount

Author: angch

2020-24/angch/main.go

@@ -60,30 +60,52 @@ func do(fileName string) (ret1 int, ret2 int) {
 	}
 
 	// log.Println(hexmap)
-
-	for _, v := range hexmap {
-		if v {
+	neighbourcount := make(map[Hex]int)
+	for c, v2 := range hexmap {
+		if v2 {
 			ret1++
+
+			for _, v := range dir {
+				v.I += c.I
+				v.J += c.J
+				v.K += c.K
+
+				neighbourcount[v]++
+			}
 		}
 	}
 
 	for day := 1; day <= 100; day++ {
 		hexmap2 := make(map[Hex]bool)
+		neighbourcount2 := make(map[Hex]int)
 		min, max := minmax(hexmap)
 		for i := min.I - 1; i <= max.I+1; i++ {
 			for j := min.J - 1; j <= max.J+1; j++ {
 				for k := min.K - 1; k <= max.K+1; k++ {
 					c := Hex{i, j, k}
-					n := neighbour(hexmap, c)
+					n := neighbourcount[c]
+					// n := neighbour(hexmap, c)
 					if hexmap[c] {
 						if n == 0 || n > 2 {
 							// hexmap2[c] = false
 						} else {
 							hexmap2[c] = true
+							for _, v := range dir {
+								v.I += c.I
+								v.J += c.J
+								v.K += c.K
+								neighbourcount2[v]++
+							}
 						}
 					} else {
 						if n == 2 {
 							hexmap2[c] = true
+							for _, v := range dir {
+								v.I += c.I
+								v.J += c.J
+								v.K += c.K
+								neighbourcount2[v]++
+							}
 						} else {
 							// hexmap2[c] = false
 						}
@@ -94,14 +116,14 @@ func do(fileName string) (ret1 int, ret2 int) {
 		hexmap = hexmap2
 
 		count := 0
-		for _, v := range hexmap {
-			if v {
+		neighbourcount = neighbourcount2
+		for _, v2 := range hexmap {
+			if v2 {
 				count++
 			}
 		}
 		ret2 = count
-		log.Println("Day", day, count)
-
+		// log.Println("Day", day, count)
 	}
 
 	return ret1, ret2
@@ -146,12 +168,11 @@ func minmax(hexmap map[Hex]bool) (Hex, Hex) {
 func neighbour(hexmap map[Hex]bool, c Hex) int {
 	count := 0
 	for _, v := range dir {
-		d := c
-		d.I += v.I
-		d.J += v.J
-		d.K += v.K
+		v.I += c.I
+		v.J += c.J
+		v.K += c.K
 
-		if hexmap[d] {
+		if hexmap[v] {
 			count++
 		}
 	}