157 lines
2.9 KiB
C++
157 lines
2.9 KiB
C++
#include <bits/stdc++.h> // {{{
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#include <version>
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#ifdef __cpp_lib_ranges_enumerate
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#include <ranges>
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namespace rv = std::views;
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namespace rs = std::ranges;
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#endif
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// https://codeforces.com/blog/entry/96344
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#pragma GCC optimize("O2,unroll-loops")
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#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
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using namespace std;
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using i32 = int32_t;
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using u32 = uint32_t;
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using i64 = int64_t;
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using u64 = uint64_t;
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using f64 = double;
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using f128 = long double;
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#if __cplusplus >= 202002L
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template <typename T>
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constexpr T MIN = std::numeric_limits<T>::min();
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template <typename T>
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constexpr T MAX = std::numeric_limits<T>::max();
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template <typename T>
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[[nodiscard]] static T sc(auto&& x) {
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return static_cast<T>(x);
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}
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template <typename T>
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[[nodiscard]] static T sz(auto&& x) {
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return static_cast<T>(x.size());
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}
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#endif
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static void NO() {
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std::cout << "NO\n";
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}
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static void YES() {
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std::cout << "YES\n";
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}
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template <typename T>
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using vec = std::vector<T>;
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#define all(x) (x).begin(), (x).end()
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#define rall(x) (x).rbegin(), (x).rend()
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#define ff first
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#define ss second
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#ifdef LOCAL
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#define db(...) std::print(__VA_ARGS__)
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#define dbln(...) std::println(__VA_ARGS__)
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#else
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#define db(...)
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#define dbln(...)
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#endif
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// }}}
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unordered_map<char, pair<i32, i32>> dirs{
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{'L', {0, -1}}, {'R', {0, 1}}, {'U', {-1, 0}}, {'D', {1, 0}}};
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void solve() {
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u32 n, m;
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cin >> n >> m;
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vec<string> grid(n);
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for (auto& e : grid)
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cin >> e;
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i32 sr, sc, er, ec;
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for (u32 r = 0; r < n; ++r) {
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for (u32 c = 0; c < m; ++c) {
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if (grid[r][c] == 'A') {
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sr = r;
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sc = c;
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} else if (grid[r][c] == 'B') {
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er = r;
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ec = c;
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}
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}
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}
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queue<pair<i32, i32>> q{{{sr, sc}}};
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vec<string> trace(n, string(m, ' '));
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auto print_trace = [&]() mutable -> void {
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string ans;
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i32 row = er, col = ec;
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while (grid[row][col] != 'A') {
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char step = trace[row][col];
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ans.push_back(step);
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row -= dirs.at(step).first;
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col -= dirs.at(step).second;
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}
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reverse(all(ans));
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cout << ans.size() << '\n' << ans << '\n';
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};
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while (!q.empty()) {
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auto [r, c] = q.front();
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q.pop();
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if (r == er && c == ec) {
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cout << "YES\n";
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print_trace();
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return;
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}
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for (auto& [letter, dir] : dirs) {
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auto& [dr, dc] = dir;
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i32 nr = r + dr;
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i32 nc = c + dc;
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if (min(nr, nc) < 0 || nr >= n || nc >= m || grid[nr][nc] == '#' ||
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trace[nr][nc] != ' ') {
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continue;
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}
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trace[nr][nc] = letter;
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q.emplace(nr, nc);
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}
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}
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cout << "NO\n";
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}
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int main() { // {{{
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std::cin.exceptions(std::cin.failbit);
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#ifdef LOCAL
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std::cerr.rdbuf(std::cout.rdbuf());
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std::cout.setf(std::ios::unitbuf);
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std::cerr.setf(std::ios::unitbuf);
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#else
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std::cin.tie(nullptr)->sync_with_stdio(false);
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#endif
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u32 tc = 1;
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// std::cin >> tc;
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for (u32 t = 0; t < tc; ++t) {
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solve();
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}
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return 0;
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}
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// }}}
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