197 lines
4.1 KiB
C++
197 lines
4.1 KiB
C++
/* Problem URL: https://cses.fi/problemset/task/1194 */
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#include <bits/stdc++.h>
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using namespace std;
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#define V vector
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#define rmin(a, b) a = min(a, b)
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#define rmax(a, b) a = max(a, b)
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#define rep(i, lim) for (int i = 0; i < (lim); i++)
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#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
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#define repv(i, v) for (auto &i : (v))
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#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
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#define sortv(v) sort(v.begin(), v.end())
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#define all(v) (v).begin(), (v).end()
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using vi = vector<int>;
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using vvi = vector<vi>;
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using vvvi = vector<vvi>;
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using vvvvi = vector<vvvi>;
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using ll = long long;
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using vl = vector<ll>;
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using vvl = vector<vl>;
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using vvvl = vector<vvl>;
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using vvvvl = vector<vvvl>;
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template<class v>
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auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
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os << vec[0];
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for (size_t i = 1; i < vec.size(); i++) {
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os << ' ' << vec[i];
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}
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os << '\n';
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<v> &vec)->istream& {
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for (auto &i : vec) {
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is >> i;
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}
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return is;
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}
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template<class v>
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auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
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for (auto &i : vec) {
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os << i[0];
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for (size_t j = 1; j < i.size(); j++) {
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os << ' ' << i[j];
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}
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os << '\n';
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}
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
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for (auto &i : vec) {
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for (auto &j : i) {
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is >> j;
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}
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}
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return is;
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}
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int main()
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{
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ios::sync_with_stdio(false);
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cin.tie(nullptr);
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int n, m;
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cin >> n >> m;
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V<string> fds(n);
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cin >> fds;
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int si, sj;
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int inf = INT32_MAX >> 1;
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queue<pair<int, int>> mq;
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vvi mdis(n, vi(m, inf));
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rep(i, n){
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rep(j, m) {
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if (fds[i][j] == 'A') {
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si = i;
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sj = j;
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continue;
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}
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if (fds[i][j] == 'M') {
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mq.emplace(i, j);
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mdis[i][j] = 0;
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}
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}
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}
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auto mbfs = [&](){
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while (!mq.empty()) {
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auto [i, j] = mq.front();
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mq.pop();
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int add[][2] = {{0, 1}, {0, -1}, {-1, 0}, {1, 0}};
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repv(k, add) {
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int id = i + k[0];
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int jd = j + k[1];
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if (id >= 0 && id < n && jd >= 0 && jd < m && fds[id][jd] != '#' && mdis[id][jd] > mdis[i][j] + 1) {
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mdis[id][jd] = mdis[i][j] + 1;
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mq.emplace(id, jd);
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}
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}
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}
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};
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mbfs();
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vvi pdis(n, vi(m, inf));
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auto bfs = [&](){
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pdis[si][sj] = 0;
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queue<pair<int, int>> q;
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q.emplace(si, sj);
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while (!q.empty()) {
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auto [i, j] = q.front();
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q.pop();
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int add[][2] = {{0, 1}, {0, -1}, {-1, 0}, {1, 0}};
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repv(k, add) {
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int id = i + k[0];
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int jd = j + k[1];
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if (id >= 0 && id < n && jd >= 0 && jd < m && fds[id][jd] == '.' && pdis[id][jd] > pdis[i][j] + 1) {
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pdis[id][jd] = pdis[i][j] + 1;
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q.emplace(id, jd);
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}
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}
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}
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};
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bfs();
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string ans;
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function<bool(int, int)> dfs = [&](int i, int j) {
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if (i < 0 || i >= n || j < 0 || j >= m) {
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return true;
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}
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if (pdis[i][j] >= mdis[i][j] || fds[i][j] == '#' || fds[i][j] == 'M') {
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return false;
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}
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int add[][3] = {{0, 1, 'R'}, {0, -1, 'L'}, {-1, 0, 'U'}, {1, 0, 'D'}};
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repv(k, add) {
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int id = i + k[0];
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int jd = j + k[1];
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if (id >= 0 && id < n && jd >= 0 && jd < m && pdis[id][jd] <= pdis[i][j]) {
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continue;
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}
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ans.push_back(k[2]);
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if (dfs(id, jd)) {
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return true;
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}
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ans.pop_back();
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}
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return false;
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};
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if (!dfs(si, sj)) {
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cout << "NO\n";
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return 0;
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}
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ans.pop_back();
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cout << "YES\n" << ans.size() << '\n';
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cout << ans << '\n';
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}
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