Day 11. part 2.

day_11/solution.go

@@ -5,6 +5,8 @@ import (
 	"strings"
 )
 
+type Stones map[uint64]uint64
+
 // task:https://adventofcode.com/2024/day/11
 func SolveBasic(input string) int {
 	stones := load(input)
@@ -13,24 +15,38 @@ func SolveBasic(input string) int {
 		stones = blink(stones)
 	}
 
-	return len(stones)
+	sum := uint64(0)
+	for _, st := range stones {
+		sum += st
+	}
+	return int(sum)
 }
 
-// task:https://adventofcode.com/2024/day/10#part2
+// task:https://adventofcode.com/2024/day/11#part2
 func SolveComplex(input string) int {
-	return 0
+	stones := load(input)
+
+	for i := 0; i < 75; i++ {
+		stones = blink(stones)
 	}
 
-func blink(before []uint64) []uint64 {
+	sum := uint64(0)
-	after := make([]uint64, 0, len(before))
+	for _, st := range stones {
-	for _, stone := range before {
+		sum += st
+	}
+	return int(sum)
+}
+
+func blink(before Stones) Stones {
+	after := Stones{}
+	for stone, count := range before {
 		if stone == 0 {
-			after = append(after, 1)
+			after[1] += count
 		} else if val := fromUint(stone); len(val)%2 == 0 {
-			after = append(after, parseUint(val[:len(val)/2]))
+			after[parseUint(val[:len(val)/2])] += count
-			after = append(after, parseUint(val[len(val)/2:]))
+			after[parseUint(val[len(val)/2:])] += count
 		} else {
-			after = append(after, stone*2024)
+			after[stone*2024] += count
 		}
 	}
 	return after
@@ -40,10 +56,10 @@ func fromUint(stone uint64) string {
 	return strconv.FormatUint(stone, 10)
 }
 
-func load(input string) []uint64 {
+func load(input string) Stones {
-	stones := []uint64{}
+	stones := Stones{}
 	for _, substring := range strings.Split(input, " ") {
-		stones = append(stones, parseUint(substring))
+		stones[parseUint(substring)]++
 	}
 	return stones
 }