103 lines
2.3 KiB
C++
103 lines
2.3 KiB
C++
#include <cassert>
|
|
#include <iostream>
|
|
#include <numeric>
|
|
#include <string>
|
|
#include <vector>
|
|
|
|
using UInt = unsigned long;
|
|
|
|
auto spin(std::string const& s, UInt num) -> std::string
|
|
{
|
|
assert(num < s.size());
|
|
|
|
std::string result;
|
|
result.reserve(s.size());
|
|
auto inserter{std::back_inserter(result)};
|
|
std::copy(s.end() - num, s.end(), inserter);
|
|
std::copy(s.begin(), s.end() - num, inserter);
|
|
return result;
|
|
}
|
|
|
|
auto exchange(std::string const& s, UInt a, UInt b) -> std::string
|
|
{
|
|
assert(a < s.size());
|
|
assert(b < s.size());
|
|
|
|
std::string result{s};
|
|
std::swap(result[a], result[b]);
|
|
return result;
|
|
}
|
|
|
|
auto partner(std::string const& s, char a, char b) -> std::string
|
|
{
|
|
std::string result;
|
|
std::transform(s.begin(), s.end(), std::back_inserter(result), [a, b](char c) {
|
|
if (c == a) {
|
|
return b;
|
|
}
|
|
if (c == b) {
|
|
return a;
|
|
}
|
|
return c;
|
|
});
|
|
|
|
return result;
|
|
}
|
|
|
|
auto main() -> int
|
|
{
|
|
std::string line;
|
|
if (!std::getline(std::cin, line)) {
|
|
std::cerr << "Unable to read line.\n";
|
|
return 1;
|
|
}
|
|
|
|
std::string programs;
|
|
programs.resize(16);
|
|
std::iota(programs.begin(), programs.end(), 'a');
|
|
|
|
std::size_t idx{0};
|
|
while (idx < line.size()) {
|
|
switch (line[idx++]) {
|
|
case ',':
|
|
break;
|
|
case 's': {
|
|
std::size_t end{0};
|
|
auto x{std::stoul(line.substr(idx), &end)};
|
|
idx += end;
|
|
programs = spin(programs, x);
|
|
break;
|
|
}
|
|
case 'x': {
|
|
std::size_t end{0};
|
|
auto x{std::stoul(line.substr(idx), &end)};
|
|
idx += end;
|
|
if (line[idx++] != '/') {
|
|
std::cerr << "Missing exchange / at " << idx - 1 << ": " << line.substr(idx - 1) << '\n';
|
|
}
|
|
auto y{std::stoul(line.substr(idx), &end)};
|
|
idx += end;
|
|
programs = exchange(programs, x, y);
|
|
break;
|
|
}
|
|
case 'p': {
|
|
auto a{line[idx++]};
|
|
if (line[idx++] != '/') {
|
|
std::cerr << "Missing partner / at " << idx - 1 << ": " << line.substr(idx - 1) << '\n';
|
|
}
|
|
auto b{line[idx++]};
|
|
programs = partner(programs, a, b);
|
|
break;
|
|
}
|
|
default:
|
|
std::cerr << "Unable to understand at index " << idx - 1 << ": " << line.substr(idx - 1)
|
|
<< '\n';
|
|
abort();
|
|
break;
|
|
}
|
|
}
|
|
|
|
std::cout << "Result: " << programs << '\n';
|
|
return 0;
|
|
}
|