day4

1 files changed, 15 insertions, 0 deletions

diff --git a/src/2015/day4/aoc.cpp b/src/2015/day4/aoc.cpp
index 1bb0d4e..ab5f301 100644
--- a/src/2015/day4/aoc.cpp
+++ b/src/2015/day4/aoc.cpp
@@ -27,4 +27,19 @@ int lead_zeros(char* s) {
   return total;
 }
 
+int day4(const char* secret, int target) {
+  char buf[128] = {0};
+  int len = strlen(secret);
+  memcpy(buf, secret, len);
+  int i = 1;
+  while (i < INT32_MAX) {
+    sprintf(buf+len, "%d", i);
+    if (lead_zeros(md5sum(buf)) >= target) {
+      break;
+    }
+    i++;
+  }
+  return i;
+}
+
 } // namespace aoc2015