1 files changed, 73 insertions, 1 deletions
diff --git a/src/2016/day14/aoc.cpp b/src/2016/day14/aoc.cpp
index c46c374..dc49f69 100644
--- a/src/2016/day14/aoc.cpp
+++ b/src/2016/day14/aoc.cpp
@@ -1,6 +1,78 @@
 #include "aoc.h"
+#include "md5.h"
+#include <map>
+#include <set>
 
 namespace aoc2016 {
 
-std::pair<int64_t, int64_t> day14(line_view) { return {0, 0}; }
+static std::map<char, std::set<size_t>> has3s;
+static std::map<char, std::set<size_t>> has5s;
+
+static bool is_equal(const char* p0, const char* p1) {
+  while (p0 < p1) {
+    if (*p0 != *p1) {
+      return false;
+    }
+    p0++;
+  }
+  return true;
+}
+
+const char* has(const char* md5, int n) {
+  const char* p = md5;
+  while (p < md5 + 32 - n + 1) {
+    if (is_equal(p, p + n - 1)) {
+      return p;
+    }
+    p++;
+  }
+  return nullptr;
+}
+
+struct md5_property {
+  std::string md5;
+  char c3 = 0;
+  char c5 = 0;
+};
+
+static void insert(char c, size_t index, std::map<char, std::set<size_t>>& hs) {
+  auto p = hs.insert({c, {index}});
+  if (!p.second) {
+    p.first->second.insert(index);
+  }
+}
+
+md5_property md5(const char* secret, size_t index) {
+  static std::vector<md5_property> md5s;
+  if (index >= md5s.size()) {
+    char buf[128] = {0};
+    int l = strlen(secret);
+    memcpy(buf, secret, l);
+    auto s = md5s.size();
+    md5s.resize(index + 1);
+    for (size_t i = s; i < md5s.size(); i++) {
+      sprintf(buf + l, "%zu", index);
+      md5s[i].md5 = std::string(md5sum(buf), 32);
+      auto pc3 = has(md5s[i].md5.c_str(), 3);
+      if (pc3 != nullptr) {
+        md5s[i].c3 = *pc3;
+        insert(*pc3, index, has3s);
+      }
+      auto pc5 = has(md5s[i].md5.c_str(), 5);
+      if (pc5 != nullptr) {
+        md5s[i].c5 = *pc5;
+        insert(*pc5, index, has5s);
+      }
+    }
+  }
+  return md5s[index];
+}
+
+void find_key(const char* secret, size_t index, int* count) {}
+
+std::pair<int64_t, int64_t> day14(line_view) {
+  // md5("abc", 30000);
+  md5("jlmsuwbz", 30000);
+  return {0, 0};
+}
 } // namespace aoc2016