Solutions for 2018 day 8

2018/puzzle-08-01.cc

@@ -0,0 +1,61 @@
+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <algorithm>
+#include <array>
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <map>
+#include <regex>
+#include <utility>
+
+using Int = std::int64_t;
+
+template<typename iterator>
+auto read_int(iterator& begin, iterator end) -> Int
+{
+  while (begin != end && *begin == ' ') {
+    ++begin;
+  }
+  Int result{0};
+  while (begin != end && std::isdigit(*begin) != 0) {
+    result *= 10;
+    result += *begin - '0';
+    ++begin;
+  }
+  return result;
+}
+
+template<typename iterator>
+auto process_string(iterator& begin, iterator end) -> Int
+{
+  Int score{0};
+  Int child_count{read_int(begin, end)};
+  Int metadata_count{read_int(begin, end)};
+  for (Int i{0}; i < child_count; ++i) {
+    score += process_string(begin, end);
+  }
+  for (Int i{0}; i < metadata_count; ++i) {
+    score += read_int(begin, end);
+  }
+  return score;
+}
+
+auto main() -> int
+{
+  std::string line;
+
+  // Read data
+  if (!std::getline(std::cin, line)) {
+    std::cerr << "Unable to read line.\n";
+    return EXIT_FAILURE;
+  }
+
+  auto begin{line.begin()};
+  Int sum{process_string(begin, line.end())};
+  std::cout << "Sum: " << sum << "\n";
+
+  return EXIT_SUCCESS;
+}

2018/puzzle-08-02.cc

@@ -0,0 +1,72 @@
+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <algorithm>
+#include <array>
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <map>
+#include <regex>
+#include <utility>
+
+using Int = std::int64_t;
+
+template<typename iterator>
+auto read_int(iterator& begin, iterator end) -> Int
+{
+  while (begin != end && *begin == ' ') {
+    ++begin;
+  }
+  Int result{0};
+  while (begin != end && std::isdigit(*begin) != 0) {
+    result *= 10;
+    result += *begin - '0';
+    ++begin;
+  }
+  return result;
+}
+
+template<typename iterator>
+auto process_string(iterator& begin, iterator end) -> Int
+{
+  Int child_count{read_int(begin, end)};
+  Int metadata_count{read_int(begin, end)};
+  std::vector<Int> child_scores;
+  child_scores.push_back(0);
+  for (Int i{0}; i < child_count; ++i) {
+    child_scores.push_back(process_string(begin, end));
+  }
+
+  Int score{0};
+  for (Int i{0}; i < metadata_count; ++i) {
+    if (child_count > 0) {
+      Int idx{read_int(begin, end)};
+      if (idx < child_scores.size()) {
+        score += child_scores[idx];
+      }
+    }
+    else {
+      score += read_int(begin, end);
+    }
+  }
+  return score;
+}
+
+auto main() -> int
+{
+  std::string line;
+
+  // Read data
+  if (!std::getline(std::cin, line)) {
+    std::cerr << "Unable to read line.\n";
+    return EXIT_FAILURE;
+  }
+
+  auto begin{line.begin()};
+  Int sum{process_string(begin, line.end())};
+  std::cout << "Sum: " << sum << "\n";
+
+  return EXIT_SUCCESS;
+}