Initial commit

2015/puzzle-17-01.cc

@@ -0,0 +1,61 @@
+#include <cassert>
+#include <cctype>
+#include <climits>
+#include <functional>
+#include <iostream>
+#include <map>
+#include <regex>
+#include <set>
+#include <string>
+#include <variant>
+
+using Quantity = unsigned long;
+constexpr Quantity total = 150;
+
+using Quantities = std::vector<Quantity>;
+
+unsigned count_combinations(Quantities::const_iterator it,
+                            Quantities::const_iterator end, Quantity amount,
+                            unsigned depth = 0) {
+  // We have no room for this container
+  std::cout << std::string(depth, ' ') << *it << ": " << amount << "\n";
+  if (amount < *it) {
+    return 0;
+  }
+
+  // Matched
+  if (amount == *it) {
+    return 1;
+  }
+
+  amount -= *it;
+  auto result = 0;
+  while (++it != end) {
+    result += count_combinations(it, end, amount, depth + 2);
+  }
+  return result;
+}
+
+unsigned count_combinations(Quantities const &containers) {
+  unsigned result = 0;
+  for (auto it = containers.begin(); it != containers.end(); ++it) {
+    result += count_combinations(it, containers.end(), total);
+  }
+  return result;
+}
+
+int main(int argc, char **argv) {
+  std::string line;
+  Quantities containers;
+  while (std::getline(std::cin, line)) {
+    containers.push_back(std::stoul(line));
+  }
+
+  // Sort containers into reverse order
+  std::sort(containers.begin(), containers.end());
+  std::reverse(containers.begin(), containers.end());
+
+  unsigned result = count_combinations(containers);
+  std::cout << "Solution: " << result << "\n";
+  return 0;
+}