Add 2017 day 7 puzzles

2017/puzzle-07-01.cc

@@ -0,0 +1,60 @@
+#include <iostream>
+#include <map>
+#include <regex>
+#include <set>
+#include <string>
+#include <vector>
+
+using UInt = unsigned long;
+
+auto main() -> int
+{
+  static std::regex top_re{R"(^([a-z]+) \((\d+)\)$)"};
+  static std::regex node_re{R"(^([a-z]+) \((\d+)\) -> (.+)$)"};
+
+  std::string line;
+  std::map<std::string, UInt> weights;
+  std::set<std::string> children_nodes;
+  std::set<std::string> maybe_root;
+
+  while (std::getline(std::cin, line) && !line.empty()) {
+    std::smatch m;
+    if (std::regex_search(line, m, node_re)) {
+      auto weight{std::stoul(m.str(2))};
+      auto node{m.str(1)};
+      auto children{m.str(3)};
+      weights.insert({node, weight});
+      maybe_root.insert(node);
+      std::size_t idx{0};
+      while (idx < children.size()) {
+        if (children[idx] == ' ' || children[idx] == ',') {
+          ++idx;
+          continue;
+        }
+
+        std::string child;
+        while (idx < children.size() && children[idx] != ',') {
+          child.push_back(children[idx]);
+          ++idx;
+        }
+        children_nodes.insert(child);
+      }
+    }
+    else if (std::regex_search(line, m, top_re)) {
+      auto weight{std::stoul(m.str(2))};
+      auto const& node{m.str(1)};
+      weights.insert({node, weight});
+      children_nodes.insert(node);
+    }
+  }
+
+  std::set<std::string> root;
+  std::set_difference(maybe_root.begin(), maybe_root.end(), children_nodes.begin(),
+                      children_nodes.end(), std::inserter(root, root.end()));
+  std::string prefix = "Root = ";
+  for (auto const& n : root) {
+    std::cout << prefix << n;
+    prefix = ", ";
+  }
+  std::cout << '\n';
+}

2017/puzzle-07-02.cc

@@ -0,0 +1,120 @@
+#include <cassert>
+#include <iostream>
+#include <map>
+#include <regex>
+#include <set>
+#include <string>
+#include <vector>
+
+using UInt = unsigned long;
+using Nodes = std::multimap<std::string, std::string>;
+using WeightMap = std::map<std::string, std::pair<UInt, UInt>>;
+
+void find_broken(Nodes const& nodes, WeightMap& weights, std::string const& node)
+{
+  auto [begin_it, end_it] = nodes.equal_range(node);
+  UInt count{0};
+  UInt total_weight{0};
+  UInt weight1{0};
+  UInt weight2{0};
+  std::string name1;
+  std::string name2;
+  for (auto it{begin_it}; it != end_it; ++it) {
+    find_broken(nodes, weights, it->second);
+    ++count;
+    auto w{weights.find(it->second)->second.second};
+    total_weight += w;
+    if (weight1 == 0) {
+      weight1 = w;
+      name1 = it->second;
+    }
+    else if (w != weight1 && weight2 == 0) {
+      weight2 = w;
+      name2 = it->second;
+    }
+    else if (w != weight1 && w != weight2) {
+      abort();
+    }
+  }
+
+  std::string wrong_name;
+  UInt wrong_weight{0};
+  UInt correct_weight{0};
+  if (weight2 != 0 && (weight1 * (count - 1) + weight2) == total_weight) {
+    wrong_name = name2;
+    wrong_weight = weight2;
+    correct_weight = weight1;
+  }
+  if (weight2 != 0 && (weight2 * (count - 1) + weight1) == total_weight) {
+    wrong_name = name1;
+    wrong_weight = weight1;
+    correct_weight = weight2;
+  }
+
+  if (wrong_weight != 0) {
+    std::cout << "Wrong node: " << wrong_name << "\n";
+    std::cout << "Total weight is " << wrong_weight << " but should be " << correct_weight << '\n';
+    std::cout << "Node weight should therefore be: "
+              << weights.find(wrong_name)->second.first + correct_weight - wrong_weight << '\n';
+    std::exit(0);
+  }
+
+  auto it{weights.find(node)};
+  assert(it != weights.end());
+  it->second.second = it->second.first + total_weight;
+}
+
+auto main() -> int
+{
+  static std::regex top_re{R"(^([a-z]+) \((\d+)\)$)"};
+  static std::regex node_re{R"(^([a-z]+) \((\d+)\) -> (.+)$)"};
+
+  std::string line;
+  WeightMap weights;
+  Nodes nodes;
+  std::set<std::string> children_nodes;
+  std::set<std::string> maybe_root;
+
+  while (std::getline(std::cin, line) && !line.empty()) {
+    std::smatch m;
+    if (std::regex_search(line, m, node_re)) {
+      auto weight{std::stoul(m.str(2))};
+      auto node{m.str(1)};
+      auto children{m.str(3)};
+      weights.insert({node, {weight, 0}});
+      maybe_root.insert(node);
+      std::size_t idx{0};
+      while (idx < children.size()) {
+        if (children[idx] == ' ' || children[idx] == ',') {
+          ++idx;
+          continue;
+        }
+
+        std::string child;
+        while (idx < children.size() && children[idx] != ',') {
+          child.push_back(children[idx]);
+          ++idx;
+        }
+        children_nodes.insert(child);
+        nodes.insert({node, child});
+      }
+    }
+    else if (std::regex_search(line, m, top_re)) {
+      auto weight{std::stoul(m.str(2))};
+      auto const& node{m.str(1)};
+      weights.insert({node, {weight, weight}});
+      children_nodes.insert(node);
+    }
+  }
+
+  std::set<std::string> root;
+  std::set_difference(maybe_root.begin(), maybe_root.end(), children_nodes.begin(),
+                      children_nodes.end(), std::inserter(root, root.end()));
+  std::string prefix = "Root = ";
+  for (auto const& n : root) {
+    std::cout << prefix << n;
+    prefix = ", ";
+  }
+  std::cout << '\n';
+  find_broken(nodes, weights, *root.begin());
+}