Initial commit

2020/puzzle-09-01.cc

@@ -0,0 +1,53 @@
+#include <algorithm>
+#include <cassert>
+#include <iostream>
+#include <list>
+#include <map>
+#include <regex>
+#include <string>
+
+template <std::size_t L> struct Buffer {
+  Buffer() {}
+
+  bool add_value(std::string const &s) {
+    unsigned long i = std::stoul(s);
+    auto size = buf_.size();
+    if (size == L && !valid(i)) {
+      return false;
+    }
+    if (size == L) {
+      buf_.pop_front();
+    }
+    buf_.push_back(i);
+    return true;
+  }
+
+private:
+  bool valid(unsigned long v) const {
+    assert(buf_.size() == L);
+    for (auto i = buf_.begin(); i != buf_.end(); ++i) {
+      auto j = i;
+      for (++j; j != buf_.end(); ++j) {
+        if (v == *i + *j) {
+          std::cout << "v = "
+                    << " " << *i << " + " << *j << "\n";
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  std::list<unsigned long> buf_;
+};
+
+int main(int argc, char **argv) {
+  Buffer<25> buf;
+  for (std::string line; std::getline(std::cin, line);) {
+    if (!buf.add_value(line)) {
+      std::cout << "Invalid: " << line << "\n";
+      return 0;
+    }
+  }
+  return 0;
+}