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#include <iostream>
#include <queue>
#include <ranges>
#include <string>
#include <tuple>
#include <vector>
struct Pos {
size_t i;
size_t j;
Pos(size_t a = 0, size_t b = 0) : i{a}, j{b} {}
bool operator==(const Pos& p) const { return i == p.i && j == p.j; }
std::vector<Pos> neighbors() const {
return {Pos(i+1, j), Pos(i-1, j), Pos(i, j+1), Pos(i, j-1)};
}
char dir(const Pos& p) const {
if (p.i == i+1 && p.j == j) return 'D';
if (p.i == i-1 && p.j == j) return 'U';
if (p.i == i && p.j == j+1) return 'R';
if (p.i == i && p.j == j-1) return 'L';
return 'X';
}
};
class Map {
public:
Map(size_t i, size_t j) : n{i}, m{j}, v(n, std::vector<bool>(m)) {}
Pos start() const { return a; }
Pos finish() const { return b; }
bool operator[](Pos p) const { return inb(p) && v[p.i][p.j]; }
friend std::istream& operator>>(std::istream& is, Map& map) {
std::string s;
is >> s;
for (size_t j = 0; j < map.m; j++)
map.readchar(s[j], map.l, j);
map.l++;
return is;
}
friend std::ostream& operator<<(std::ostream& os, const Map& map) {
for (size_t i = 0; i < map.n; i++) {
for (size_t j = 0; j < map.m; j++) {
if (map.a == Pos(i, j)) os << 'A';
else if (map.b == Pos(i, j)) os << 'B';
else os << (map.v[i][j] ? '.' : '#');
}
os << "\n";
}
return os;
}
template<typename T>
using Overlay = std::pair<T, std::vector<std::vector<T>>>;
template<typename T>
Overlay<T> overlay(T t) const {
auto ov = std::vector<std::vector<T>>(n, std::vector(m, t));
return {t, ov};
}
template<typename T>
T at(const Overlay<T>& ov, Pos p) const {
return inb(p) ? ov.second[p.i][p.j] : ov.first;
}
template<typename T>
void set(Overlay<T>& ov, Pos p, T val) const {
if (inb(p)) ov.second[p.i][p.j] = val;
}
private:
size_t l{0};
size_t n;
size_t m;
Pos a;
Pos b;
std::vector<std::vector<bool>> v;
void readchar(char c, size_t i, size_t j) {
v[i][j] = c != '#';
if (c == 'A') a = {i, j};
if (c == 'B') b = {i, j};
}
bool inb(Pos p) const { return p.i < n && p.j < m; }
};
int main() {
size_t n, m;
std::cin >> n >> m;
Map map(n, m);
for (size_t i = 0; i < n; i++)
std::cin >> map;
constexpr size_t inf{999999999};
auto d = map.overlay<size_t>(inf);
std::queue<std::pair<Pos, size_t>> q;
q.push({map.start(), 0});
while (!q.empty()) {
auto [p, w] = q.front();
q.pop();
if (!map[p] || map.at(d, p) != inf) continue;
map.set(d, p, w);
for (auto x : p.neighbors()) q.push({x, w+1});
}
if (map.at(d, map.finish()) == inf) {
std::cout << "NO\n";
} else {
std::cout << "YES\n" << map.at(d, map.finish()) << "\n";
// Backtrack
Pos p = map.finish();
std::vector<char> path;
do {
for (auto x : p.neighbors()) {
if (map.at(d, x) == map.at(d, p)-1) {
path.push_back(x.dir(p));
p = x;
break;
}
}
} while (p != map.start());
for (auto c : path | std::views::reverse)
std::cout << c;
std::cout << "\n";
}
}
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