4th day

4th_day/2/main.cpp

@@ -0,0 +1,77 @@
+#include <cassert>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+vector<string> get_input_from_file(const string &FILE_NAME) {
+  ifstream file(FILE_NAME);
+  vector<string> result;
+  string s, first_line;
+  size_t length;
+
+  if (getline(file, first_line)) {
+    first_line = "." + first_line + ".";
+    length = first_line.length();
+  }
+
+  result.push_back(string(length, '.'));
+  result.push_back(first_line);
+
+  while (getline(file, s)) {
+    result.push_back("." + s + ".");
+  }
+  result.push_back(string(length, '.'));
+  return result;
+}
+
+bool is_available(const string &current_line, const string &next_line,
+                  const string &prev_line, const int pos) {
+  assert(current_line[pos] == '@');
+
+  int count = 0;
+  const char ROLL = '@';
+
+  for (int i = pos - 1; i <= pos + 1; i++) {
+    if (prev_line[i] == ROLL) {
+      count++;
+    }
+
+    if (next_line[i] == ROLL) {
+      count++;
+    }
+  }
+
+  if (current_line[pos - 1] == ROLL) {
+    count++;
+  }
+
+  if (current_line[pos + 1] == ROLL) {
+    count++;
+  }
+
+  return count < 4;
+}
+
+int main() {
+  string const FILE_NAME = "input.txt";
+  vector<string> input = get_input_from_file(FILE_NAME);
+  int removed_count = 0;
+
+  for (int i = 1; i < input.size() - 1; i++) {
+    for (int j = 1; j < input[i].size() - 1; j++) {
+      if (input[i][j] == '@' &&
+          is_available(input[i], input[i + 1], input[i - 1], j)) {
+        input[i][j] = '.';
+        i = 1;
+        j = 1;
+        removed_count++;
+      }
+    }
+  }
+  cout << removed_count;
+
+  return 0;
+}