Add 2016 day 19 puzzles

2016/puzzle-19-01.cc

@@ -0,0 +1,36 @@
+//
+// Created by Matthew Gretton-Dann on 07/12/2021.
+//
+
+#include <iostream>
+#include <list>
+#include <string>
+
+auto main() -> int
+{
+  std::string line;
+  if (!std::getline(std::cin, line)) {
+    std::cerr << "Unable to read input.\n";
+    return 1;
+  }
+  auto n{std::stoul(line)};
+  std::list<unsigned long> elves;
+  for (unsigned long i{1}; i <= n; ++i) {
+    elves.push_back(i);
+  }
+  auto it{elves.begin()};
+  while (elves.size() > 1) {
+    std::cout << *it << " takes ";
+    ++it;
+    if (it == elves.end()) {
+      it = elves.begin();
+    }
+    std::cout << *it << '\n';
+    it = elves.erase(it);
+    if (it == elves.end()) {
+      it = elves.begin();
+    }
+  }
+
+  std::cout << "Last elf: " << elves.front() << '\n';
+}