Initial commit

2015/puzzle-04-02.cc

@@ -0,0 +1,40 @@
+#include <algorithm>
+#include <cassert>
+#include <iostream>
+#include <set>
+#include <string>
+
+#include <openssl/evp.h>
+
+using MD5Digest = unsigned char[EVP_MAX_MD_SIZE];
+
+unsigned int md5(MD5Digest digest, std::string const &s) {
+    EVP_MD const* md{EVP_md5()};
+    unsigned int md_len;
+
+    EVP_MD_CTX* md_ctxt{EVP_MD_CTX_new()};
+    assert(md_ctxt != NULL);
+    EVP_DigestInit_ex2(md_ctxt, md, NULL);
+    EVP_DigestUpdate(md_ctxt, s.data(), s.length());
+    EVP_DigestFinal_ex(md_ctxt, digest, &md_len);
+    return md_len;
+}
+
+bool is_valid(std::string const &s) {
+  MD5Digest digest;
+  auto len = md5(digest, s);
+  assert(len >= 3);
+  return digest[0] == 0 && digest[1] == 0 && digest[2] == 0;
+}
+
+int main(int argc, char **argv) {
+  for (std::string line; std::getline(std::cin, line);) {
+    unsigned i = 0;
+    while (!is_valid(line + std::to_string(i))) {
+      ++i;
+    }
+    std::cout << "Value = " << i << "\n";
+  }
+
+  return 0;
+}