Day 4, go this time because fast.

1 files changed, 38 insertions, 0 deletions

diff --git a/day4.go b/day4.go
new file mode 100644
index 0000000..ebf8810
--- /dev/null
+++ b/day4.go
@@ -0,0 +1,38 @@
+package main
+
+import (
+	"bytes"
+	"crypto/md5"
+	"fmt"
+	"strconv"
+)
+
+func hash(secret []byte, x int64) [16]byte {
+	str := strconv.AppendInt(secret, x, 10)
+	return md5.Sum(str)
+}
+
+func check(hash [16]byte, target []byte, length int) bool {
+	str := []byte(fmt.Sprintf("%x", hash))
+	return bytes.Equal(str[:length], target[:length])
+}
+
+func main() {
+	secret := []byte("iwrupvqb")
+	target := []byte("000000")
+	x := int64(1)
+	got5, got6 := false, false
+
+	for !(got5 && got6) {
+		h := hash(secret, x)
+		if !got5 && check(h, target, 5) {
+			fmt.Println("Lowest number for 5-zeroes hash:", x)
+			got5 = true
+		}
+		if !got6 && check(h, target, 6) {
+			fmt.Println("Lowest number for 6-zeroes hash:", x)
+			got6 = true
+		}
+		x += 1
+	}
+}