Day 7

d7/main.cxx

@@ -0,0 +1,93 @@
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <map>
+#include <algorithm>
+#include <queue>
+
+constexpr unsigned int hash(const char *s, int off = 0)
+{
+  return !s[off] ? 5381 : (hash(s, off + 1) * 33) ^ s[off];
+}
+
+std::string topDir(std::string &path)
+{
+  std::string dir;
+  for (int i = path.size() - 1; i >= 0; i--)
+  {
+    if (path[i] != ' ')
+      dir.push_back(path[i]);
+    else
+      break;
+  }
+  std::reverse(dir.begin(), dir.end());
+  return dir;
+}
+
+void handleComd(const std::string &operation, std::string &path, std::map<unsigned int, long> &dirs)
+{
+  std::stringstream iss(operation);
+  std::string comd;
+  iss >> comd;
+
+  switch (hash(comd.c_str()))
+  {
+  case hash("$"):
+    iss >> comd;
+    if (comd != "cd")
+      return;
+
+    iss >> comd;
+    if (comd == "..")
+    {
+      for (int i = topDir(path).length(); i >= 0; i--)
+        path.pop_back();
+    }
+    else if (comd != "/")
+      path.append(" " + comd);
+    return;
+
+  case hash("dir"):
+    return;
+
+  default:
+    std::stringstream pathss(path);
+    std::string tmpPath, dir;
+    int pathLen = std::count(path.begin(), path.end(), ' ');
+    for (int i{0}; i < pathLen; i++)
+    {
+      pathss >> dir;
+      tmpPath += " " + dir;
+      dirs[hash(tmpPath.c_str())] += std::stoi(comd);
+    }
+    dirs[hash(" ")] += std::stoi(comd);
+
+    return;
+  }
+}
+
+int main()
+{
+  std::ifstream file{"../d7/input.txt"};
+  std::map<unsigned int, long> dirs{};
+
+  std::string line, path;
+  while (std::getline(file, line))
+    handleComd(line, path, dirs);
+
+  int sum{0};
+  for (auto &[_, size] : dirs)
+    if (size <= 100000)
+      sum += size;
+
+  long toDelete = 30000000 - (70000000 - dirs[hash(" ")]);
+
+  std::priority_queue<int, std::vector<int>, std::greater<int>> pq;
+  for (auto &[_, size] : dirs)
+    if (size >= toDelete)
+      pq.push(size);
+
+  std::cout << pq.top() << std::endl;
+  return 0;
+}