Added older advents

advent_of_code_2015/day4/main1.cc

@@ -0,0 +1,24 @@
+#include <iostream>
+#include <string>
+
+#include "md5.hpp"
+
+using namespace std;
+
+int main()
+{
+
+    string prefix = "bgvyzdsv";
+
+    for (size_t idx = 0; ; ++idx)
+    {
+        string test = prefix + to_string(idx);
+
+        string hash = md5(test);
+        if (hash.find_first_not_of('0') == 6) //5 for solution 1
+        {
+            cout << test << "\n";
+            return 0;
+        }
+    }
+}