From 05901e23db671e76824aa68de011920f57ffb38e Mon Sep 17 00:00:00 2001
From: Nathan Lasseter <Nathan Lasseter nathan@bytemark.co.uk>
Date: Fri, 4 Dec 2015 18:20:40 +0000
Subject: Made day4 C. Yay!

---
 day4.c  | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 day4.go | 38 --------------------------------------
 2 files changed, 53 insertions(+), 38 deletions(-)
 create mode 100644 day4.c
 delete mode 100644 day4.go

diff --git a/day4.c b/day4.c
new file mode 100644
index 0000000..ae3fb94
--- /dev/null
+++ b/day4.c
@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <openssl/md5.h>
+
+unsigned char* secret = "iwrupvqb";
+unsigned char* target = "000000";
+unsigned char result[MD5_DIGEST_LENGTH];
+
+void hash(int i) {
+  char num[12];
+  sprintf(num, "%d", i);
+  char str[22] = "";
+  strcat(str, secret);
+  strcat(str, num);
+
+  MD5(str, strlen(str), result);
+}
+
+int tohex() {
+  int i, dg = 0;
+  for(i = 0; i < 4; i++) {
+    dg <<= 8;
+    dg += result[i];
+  }
+  return dg;
+}
+
+int check(int len) {
+  unsigned char str[8];
+  int dg = tohex();
+  sprintf(str, "%08x", dg);
+  return strncmp(str, target, len) == 0;
+}
+
+int main() {
+  int i = 1, got5 = 0, got6 = 0;
+
+  while(!(got5 && got6)) {
+    hash(i);
+    if(!got5 && check(5)) {
+      got5 = 1;
+      printf("Lowest number for 5-zeroes hash: %d\n", i);
+    }
+    if(!got6 && check(6)) {
+      got6 = 1;
+      printf("Lowest number for 6-zeroes hash: %d\n", i);
+    }
+    i++;
+  }
+
+  return 0;
+}
diff --git a/day4.go b/day4.go
deleted file mode 100644
index ebf8810..0000000
--- a/day4.go
+++ /dev/null
@@ -1,38 +0,0 @@
-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
-	}
-}
-- 
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