day02 part2

2024/day02/part2.cc

@@ -0,0 +1,63 @@
+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <sstream>
+
+class report {
+  std::vector<int> levels;
+public:
+  bool safe();
+  friend std::istream& operator>>(std::istream& stream, report& r);
+  friend std::ostream& operator<<(std::ostream& stream, report& r);
+};
+
+std::istream& operator>>(std::istream& stream, report& r) {
+  r.levels.clear();
+  std::string s;
+  std::getline(stream, s, '\n');
+  std::stringstream ss(s);
+  int level;
+  while (ss >> level) {
+    r.levels.emplace_back(level);
+  }
+  return stream;
+}
+
+std::ostream& operator<<(std::ostream& stream, report& r) {
+  stream << "report{";
+  for (auto elem : r.levels) {
+    stream << elem << ",";
+  }
+  stream << "}";
+  return stream;
+}
+
+bool report::safe() {
+  for (size_t index = 0; index < levels.size(); index++) {
+    std::vector<int> tmp(levels);
+    tmp.erase(tmp.begin() + index);
+    if (std::adjacent_find(tmp.begin(), tmp.end(), [](int a, int b) {
+        return a - b < 1 || a - b > 3;
+      }) == tmp.end()) {
+      return true;
+    }
+    if (std::adjacent_find(tmp.begin(), tmp.end(), [](int a, int b) {
+        return b - a < 1 || b - a > 3;
+      }) == tmp.end()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+int main() {
+  report r;
+  int count = 0;
+  while (std::cin >> r) {
+    if (r.safe()) {
+      count++;
+    }
+  }
+  std::cout << count << std::endl;
+  return EXIT_SUCCESS;
+}