41 lines
1.0 KiB
C++
41 lines
1.0 KiB
C++
//
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// Created by Matthew Gretton-Dann on 07/12/2021.
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//
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#include <iostream>
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#include <numeric>
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#include <string>
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auto main() -> int
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{
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std::string line;
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if (!std::getline(std::cin, line)) {
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std::cerr << "Unable to get line.\n";
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return 1;
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}
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line = '.' + line + '.';
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unsigned safe_count{0};
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constexpr unsigned row_count{400000};
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for (unsigned row{0}; row < row_count; ++row) {
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safe_count = std::accumulate(line.begin(), line.end(), safe_count,
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[](unsigned a, char c) { return a + (c == '.' ? 1 : 0); }) -
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2;
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std::string next_line{"."};
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next_line.reserve(line.size());
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for (unsigned i = 1; i < line.size() - 1; ++i) {
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auto check{line.substr(i - 1, 3)};
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if (check == "^^." || check == ".^^" || check == "^.." || check == "..^") {
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next_line += '^';
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}
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else {
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next_line += '.';
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}
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}
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next_line += '.';
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line = next_line;
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}
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std::cout << "Number of safe spots: " << safe_count << '\n';
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return 0;
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} |