4 files changed, 70 insertions, 0 deletions
diff --git a/2021/06/example b/2021/06/example
new file mode 100644
index 0000000..55129f1
--- /dev/null
+++ b/2021/06/example
@@ -0,0 +1 @@
+3,4,3,1,2
diff --git a/2021/06/first.go b/2021/06/first.go
new file mode 100644
index 0000000..efb77be
--- /dev/null
+++ b/2021/06/first.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	g := make([]int, 9)
+
+	s := bufio.NewReader(os.Stdin)
+	for {
+		buf := make([]byte, 2)
+		if n, _ := s.Read(buf); n == 0 {
+			break
+		}
+		g[buf[0]-'0']++
+	}
+	for d := 0; d <= 80; d++ {
+		fmt.Printf("%+v\n", g)
+		n := g[0]
+		for i := 0; i < 8; i++ {
+			g[i] = g[i+1]
+		}
+		g[6] += n
+		g[8] = n
+	}
+	total := 0
+	for i := 0; i < 8; i++ {
+		total += g[i]
+	}
+	fmt.Printf("%d\n", total)
+}
diff --git a/2021/06/input b/2021/06/input
new file mode 100644
index 0000000..445de95
--- /dev/null
+++ b/2021/06/input
@@ -0,0 +1 @@
+1,1,3,1,3,2,1,3,1,1,3,1,1,2,1,3,1,1,3,5,1,1,1,3,1,2,1,1,1,1,4,4,1,2,1,2,1,1,1,5,3,2,1,5,2,5,3,3,2,2,5,4,1,1,4,4,1,1,1,1,1,1,5,1,2,4,3,2,2,2,2,1,4,1,1,5,1,3,4,4,1,1,3,3,5,5,3,1,3,3,3,1,4,2,2,1,3,4,1,4,3,3,2,3,1,1,1,5,3,1,4,2,2,3,1,3,1,2,3,3,1,4,2,2,4,1,3,1,1,1,1,1,2,1,3,3,1,2,1,1,3,4,1,1,1,1,5,1,1,5,1,1,1,4,1,5,3,1,1,3,2,1,1,3,1,1,1,5,4,3,3,5,1,3,4,3,3,1,4,4,1,2,1,1,2,1,1,1,2,1,1,1,1,1,5,1,1,2,1,5,2,1,1,2,3,2,3,1,3,1,1,1,5,1,1,2,1,1,1,1,3,4,5,3,1,4,1,1,4,1,4,1,1,1,4,5,1,1,1,4,1,3,2,2,1,1,2,3,1,4,3,5,1,5,1,1,4,5,5,1,1,3,3,1,1,1,1,5,5,3,3,2,4,1,1,1,1,1,5,1,1,2,5,5,4,2,4,4,1,1,3,3,1,5,1,1,1,1,1,1
diff --git a/2021/06/second.go b/2021/06/second.go
new file mode 100644
index 0000000..c64aa61
--- /dev/null
+++ b/2021/06/second.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	g := make([]int, 9)
+
+	s := bufio.NewReader(os.Stdin)
+	for {
+		buf := make([]byte, 2)
+		if n, _ := s.Read(buf); n == 0 {
+			break
+		}
+		g[buf[0]-'0']++
+	}
+	for d := 0; d <= 256; d++ {
+		fmt.Printf("%+v\n", g)
+		n := g[0]
+		for i := 0; i < 8; i++ {
+			g[i] = g[i+1]
+		}
+		g[6] += n
+		g[8] = n
+	}
+	total := 0
+	for i := 0; i < 8; i++ {
+		total += g[i]
+	}
+	fmt.Printf("%d\n", total)
+}