78 lines
1.3 KiB
C++
78 lines
1.3 KiB
C++
#include <fstream>
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#include <iostream>
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#include <vector>
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struct position
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{
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int x;
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int y;
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};
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int remove_paper_rolls(std::vector<std::string> &lines)
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{
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const position positions[] = {
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{ -1, -1 },
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{ 0, -1 },
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{ 1, -1 },
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{ -1, 0 },
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{ 1, 0 },
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{ -1, 1 },
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{ 0, 1 },
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{ 1, 1 },
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};
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int removed_count = 0;
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std::vector<std::string> new_lines;
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for (int y = 0; y < lines.size(); y++) {
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new_lines.push_back("");
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for (int x = 0; x < lines[y].size(); x++) {
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if (lines[y][x] == '.') {
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new_lines[y].append(".");
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continue;
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}
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int amount = 0;
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for (position pos : positions) {
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int check_x = x + pos.x, check_y = y + pos.y;
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if (check_x < 0 || check_y < 0 || check_x >= lines[y].size() || check_y >= lines.size())
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continue;
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if (lines[check_y][check_x] == '@') amount++;
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}
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if (amount < 4) {
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new_lines[y].append(".");
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removed_count++;
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} else {
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new_lines[y].append("@");
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}
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}
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}
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lines = new_lines;
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return removed_count;
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}
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int main()
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{
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std::ifstream file("input.txt");
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std::vector<std::string> lines;
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std::string line;
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while (getline(file, line)) lines.push_back(line);
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int removed = 0, total_removed = 0;
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do {
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removed = remove_paper_rolls(lines);
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total_removed += removed;
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} while (removed > 0);
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std::cout << total_removed << std::endl;
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}
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