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working vlad's lab1

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pajjilykk
2025-10-04 19:28:06 +07:00
parent fe382045b9
commit 875c54c6f2
4 changed files with 141 additions and 79 deletions
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1
others/vlad`s/lab1/compile.sh
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g++ task11.cpp -o task11

13
others/vlad`s/lab1/file.in
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aabbcc
bookkeeper
Mississippi
x
aa
aba
aaa
baaa
aaab
abba
1222333
(four spaces)
--====

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others/vlad`s/lab1/in.txt Normal file
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aaaaabababbabababaaabbbbabababbbaabbaabbabb

205
others/vlad`s/lab1/task11.cpp
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@@ -1,95 +1,170 @@
#include <iostream> #include <unistd.h>
#include <fstream>
#include <string>
#include <sys/stat.h> #include <sys/stat.h>
#include <cerrno> #include <fcntl.h>
#include <cstdlib> #include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
static bool file_exists(const std::string &path) { #define RBUFSZ 4096
struct stat st{}; #define WBUFSZ 4096
return ::stat(path.c_str(), &st) == 0;
static void die_perror(const char *what, const char *path, int exit_code) {
int saved = errno;
char msg[512];
if (path) {
snprintf(msg, sizeof(msg), "%s: %s: %s\n", what, path, strerror(saved));
} else {
snprintf(msg, sizeof(msg), "%s: %s\n", what, strerror(saved));
}
(void) write(STDERR_FILENO, msg, strlen(msg));
_exit(exit_code);
} }
static std::string make_out_name(const std::string &in) { static long long parse_ll(const char *s) {
std::size_t pos = in.find_last_of('.'); char *end = NULL;
if (pos == std::string::npos) return in + ".out";
return in.substr(0, pos) + ".out";
}
static bool parse_nonneg_ll(const char *s, long long &out) {
if (!s || *s == '\0') return false;
char *end = nullptr;
errno = 0; errno = 0;
long long v = std::strtoll(s, &end, 10); long long v = strtoll(s, &end, 10);
if (errno != 0 || end == s || *end != '\0') return false; if (errno != 0 || end == s || *end != '\0' || v < 0) {
if (v < 0) return false; errno = EINVAL;
out = v; return -1;
return true; }
return v;
} }
int main(int argc, char *argv[]) { int main(int argc, char *argv[]) {
if (argc != 3) { if (argc != 4) {
std::cerr << "Usage: " << argv[0] << " input_file replace_count\n"; const char *usage =
"Usage: lab1_var11 <input.txt> <output.txt> <max_replacements>\n"
"Variant 11: for every pair of identical consecutive characters, replace the second with a space.\n"
" Stop after <max_replacements> replacements globally.\n";
(void) write(STDERR_FILENO, usage, strlen(usage));
return -1; return -1;
} }
std::string in_path = argv[1]; const char *in_path = argv[1];
long long target = 0; const char *out_path = argv[2];
if (!parse_nonneg_ll(argv[2], target)) { long long cap = parse_ll(argv[3]);
std::cerr << "Usage: " << argv[0] << " input_file replace_count\n"; if (cap < 0) {
return -1; die_perror("invalid max_replacements", argv[3], -1);
} }
if (!file_exists(in_path)) { int in_fd = open(in_path, O_RDONLY);
std::cerr << "Error: input file does not exist.\n"; if (in_fd < 0) {
return -1; die_perror("open input failed", in_path, -1);
} }
std::ifstream in(in_path); mode_t filePerms = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH; /* rw-rw-rw- */
if (!in) { int out_fd = open(out_path, O_CREAT | O_WRONLY | O_TRUNC, filePerms);
std::cerr << "Error: cannot open input file.\n"; if (out_fd < 0) {
return -1; die_perror("open output failed", out_path, -1);
} }
std::string out_path = make_out_name(in_path); char rbuf[RBUFSZ];
std::ofstream out(out_path); char wbuf[WBUFSZ];
if (!out) { size_t wlen = 0;
std::cerr << "Error: cannot create output file.\n";
return -1;
}
long long replacements = 0; /* state */
std::string line; long long total_replacements = 0;
int replacing_enabled = 1;
while (std::getline(in, line)) { int have_prev = 0;
if (!line.empty() && replacements < target) { unsigned char prev = 0;
for (std::size_t i = 1; i < line.size() && replacements < target; ++i) {
if (line[i] == line[i - 1]) { for (;;) {
if (line[i] != ' ') { ssize_t n = read(in_fd, rbuf, sizeof(rbuf));
line[i] = ' '; if (n > 0) {
++replacements; for (ssize_t i = 0; i < n; i++) {
unsigned char c = (unsigned char) rbuf[i];
if (!have_prev) {
/* buffer first byte of a potential pair */
prev = c;
have_prev = 1;
continue;
}
if (c == prev) {
/* non-overlapping pair found: output prev, then second element possibly replaced */
unsigned char out1 = prev;
unsigned char out2 = c;
if (replacing_enabled && total_replacements < cap) {
out2 = ' ';
total_replacements++;
if (total_replacements == cap) {
replacing_enabled = 0;
}
} else {
replacing_enabled = 0;
} }
/* write out1 */
if (wlen == sizeof(wbuf)) {
ssize_t wrote = write(out_fd, wbuf, wlen);
if (wrote < 0 || (size_t) wrote != wlen) die_perror("write failed", out_path, -1);
wlen = 0;
}
wbuf[wlen++] = (char) out1;
/* write out2 */
if (wlen == sizeof(wbuf)) {
ssize_t wrote = write(out_fd, wbuf, wlen);
if (wrote < 0 || (size_t) wrote != wlen) die_perror("write failed", out_path, -1);
wlen = 0;
}
wbuf[wlen++] = (char) out2;
/* consume pair: reset have_prev so next byte starts a new potential pair */
have_prev = 0;
} else {
/* no pair: output prev, shift window to c */
if (wlen == sizeof(wbuf)) {
ssize_t wrote = write(out_fd, wbuf, wlen);
if (wrote < 0 || (size_t) wrote != wlen) die_perror("write failed", out_path, -1);
wlen = 0;
}
wbuf[wlen++] = (char) prev;
prev = c;
have_prev = 1;
} }
} }
} } else if (n == 0) {
out << line; /* flush any pending single prev */
if (!in.eof()) out << '\n'; if (have_prev) {
if (!out) { if (wlen == sizeof(wbuf)) {
std::cerr << "Error: write error.\n"; ssize_t wrote = write(out_fd, wbuf, wlen);
return -1; if (wrote < 0 || (size_t) wrote != wlen) die_perror("write failed", out_path, -1);
wlen = 0;
}
wbuf[wlen++] = (char) prev;
have_prev = 0;
}
if (wlen > 0) {
ssize_t wrote = write(out_fd, wbuf, wlen);
if (wrote < 0 || (size_t) wrote != wlen) die_perror("write failed", out_path, -1);
wlen = 0;
}
break;
} else {
die_perror("read failed", in_path, -1);
} }
} }
if (!in.eof() && in.fail()) { if (close(in_fd) < 0) {
std::cerr << "Error: read error.\n"; die_perror("close input failed", in_path, -1);
return -1; }
if (close(out_fd) < 0) {
die_perror("close output failed", out_path, -1);
} }
if (replacements != target) { char res[64];
std::cerr << "Error: could not perform exactly requested replacements.\n"; int m = snprintf(res, sizeof(res), "%lld\n", total_replacements);
return -1; if (m > 0) {
(void) write(STDOUT_FILENO, res, (size_t) m);
} }
std::cout << replacements << std::endl; int exit_code = (int) (total_replacements & 0xFF);
return 0; return exit_code;
} }