72 lines
2.0 KiB
C++
72 lines
2.0 KiB
C++
// Task 11: In every pair of identical adjacent characters, replace the second with a space.
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// Usage: ./task11 <input_file> -> writes "<name>.out" and prints replacements count.
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#include <iostream>
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#include <fstream>
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#include <string>
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#include <sys/stat.h>
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static bool file_exists(const std::string &path) {
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struct stat st{};
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return ::stat(path.c_str(), &st) == 0;
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}
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static std::string make_out_name(const std::string &in) {
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std::size_t pos = in.find_last_of('.');
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if (pos == std::string::npos) return in + ".out";
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return in.substr(0, pos) + ".out";
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}
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int main(int argc, char *argv[]) {
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if (argc != 2) {
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std::cerr << "Usage: " << argv[0] << " <input_file>\n";
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return -1;
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}
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std::string in_path = argv[1];
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if (!file_exists(in_path)) {
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std::cerr << "Error: input file does not exist.\n";
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return -1;
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}
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std::ifstream in(in_path);
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if (!in) {
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std::cerr << "Error: cannot open input file.\n";
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return -1;
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}
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std::string out_path = make_out_name(in_path);
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std::ofstream out(out_path);
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if (!out) {
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std::cerr << "Error: cannot create output file.\n";
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return -1;
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}
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long long replacements = 0;
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std::string line;
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while (std::getline(in, line)) {
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if (!line.empty()) {
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for (std::size_t i = 1; i < line.size(); ++i) {
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if (line[i] == line[i - 1]) {
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if (line[i] != ' ') {
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line[i] = ' ';
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++replacements;
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}
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// Move to next position; overlapping pairs like "aaa":
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// i at 2 will compare line[2] with line[1] (now space) → no double count.
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}
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}
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}
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out << line;
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if (!in.eof()) out << '\n';
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if (!out) {
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std::cerr << "Error: write error.\n";
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return -1;
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}
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}
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std::cout << replacements << std::endl;
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return static_cast<int>(replacements);
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}
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