Initial commit

2015/puzzle-08-01.cc

@@ -0,0 +1,80 @@
+#include <cassert>
+#include <functional>
+#include <iostream>
+#include <map>
+#include <regex>
+#include <string>
+#include <variant>
+
+enum class State { Begin, Normal, Escape, Hex1, Hex2, End };
+
+std::string unescape(std::string const &s) {
+  std::string unescaped;
+  static const std::string hex = "0123456789abcdef0123456789ABCDEF";
+
+  State state = State::Begin;
+  unsigned char byte = 0;
+  for (auto c : s) {
+    switch (state) {
+    case State::Begin:
+      assert(c == '"');
+      state = State::Normal;
+      break;
+    case State::Normal:
+      if (c == '\\') {
+        state = State::Escape;
+      } else if (c == '"') {
+        state = State::End;
+      } else {
+        unescaped += c;
+      }
+      break;
+    case State::Escape:
+      if (c == '\\' || c == '"') {
+        state = State::Normal;
+        unescaped += c;
+      } else if (c == 'x') {
+        byte = 0;
+        state = State::Hex1;
+      } else {
+        assert(false);
+      }
+      break;
+    case State::Hex1: {
+      auto idx = hex.find(c);
+      assert(idx != std::string::npos);
+      byte = idx & 0xf;
+      state = State::Hex2;
+      break;
+    }
+    case State::Hex2: {
+      auto idx = hex.find(c);
+      assert(idx != std::string::npos);
+      byte = (byte << 4) + (idx & 0xf);
+      unescaped += (char)byte;
+      state = State::Normal;
+      break;
+    }
+    case State::End:
+      assert(false);
+    }
+  }
+  return unescaped;
+}
+
+int main(int argc, char **argv) {
+  unsigned len = 0;
+
+  // Parse the input
+  for (std::string line; std::getline(std::cin, line);) {
+    std::string unescaped = unescape(line);
+    len += line.length() - unescaped.length();
+    std::cout << line << ": " << line.length() << " written bytes, "
+              << unescaped.length() << " memory bytes, difference: "
+              << line.length() - unescaped.length() << "\n";
+  }
+
+  std::cout << len << "\n";
+
+  return 0;
+}