✅ strings, trie

submissions/ICPC/Maratona de Programação da SBC 2012 Sub-Regional/Palavras.cpp

@@ -0,0 +1,181 @@
+#include <bits/stdc++.h>
+using namespace std;
+#ifdef LOCAL
+#include "debug.cpp"
+#else
+#define dbg(...) 42
+#endif
+#define endl '\n'
+#define fastio                      \
+  ios_base::sync_with_stdio(false); \
+  cin.tie(0);                       \
+  cout.tie(0);
+#define len(__x) (int)__x.size()
+using ll = long long;
+using ull = unsigned long long;
+using ld = long double;
+using vll = vector<ll>;
+using pll = pair<ll, ll>;
+using vll2d = vector<vll>;
+using vi = vector<int>;
+using vi2d = vector<vi>;
+using pii = pair<int, int>;
+using vii = vector<pii>;
+using vc = vector<char>;
+#define all(a) a.begin(), a.end()
+#define pb(___x) push_back(___x)
+#define mp(___a, ___b) make_pair(___a, ___b)
+#define eb(___x) emplace_back(___x)
+
+// vector<string> dir({"LU", "U", "RU", "R", "RD", "D",
+// "LD", "L"}); int dx[] = {-1, -1, -1, 0, 1, 1, 1, 0}; int
+// dy[] = {-1, 0, 1, 1, 1, 0, -1, -1};
+vector<string> dir({"U", "R", "D", "L"});
+int dx[] = {-1, 0, 1, 0};
+int dy[] = {0, 1, 0, -1};
+
+const ll oo = 1e18;
+int T(1);
+
+// Trie
+//
+// trie T() constroi uma trie para o alfabeto das letras
+// minusculas trie T(tamanho do alfabeto, menor caracter)
+// tambem pode ser usado
+//
+// T.insert(s) - O(|s|*sigma)
+// T.erase(s) - O(|s|)
+// T.find(s) retorna a posicao, 0 se nao achar - O(|s|)
+// T.count_pref(s) numero de strings que possuem s como
+// prefixo - O(|s|)
+//
+// Nao funciona para string vazia
+
+struct trie {
+  vi2d to;
+  vi end, pref;
+  int sigma;
+  char norm;
+
+  trie(int sigma_ = 26, char norm_ = 'a')
+    : sigma(sigma_), norm(norm_) {
+    to = {vector<int>(sigma)};
+    end = {0}, pref = {0};
+  }
+
+  bool is_end(int node) { return end[node] != 0; }
+
+  int next(int node, char key) {
+    return to[node][key - norm];
+  }
+
+  void insert(const string &s) {
+    int x = 0;
+    for (auto c : s) {
+      int &nxt = to[x][c - norm];
+      if (!nxt) {
+        nxt = len(to);
+        to.push_back(vi(sigma));
+        end.emplace_back(0), pref.emplace_back(0);
+      }
+      x = nxt, pref[x]++;
+    }
+    end[x]++, pref[0]++;
+  }
+  void erase(const string &s) {
+    int x = 0;
+    for (char c : s) {
+      int &nxt = to[x][c - norm];
+      x = nxt, pref[x]--;
+      if (!pref[x]) nxt = 0;
+    }
+    end[x]--, pref[0]--;
+  }
+  int find(const string &s) {
+    int x = 0;
+    for (auto c : s) {
+      x = to[x][c - norm];
+      if (!x) return 0;
+    }
+    return x;
+  }
+  int count_pref(const string &s) { return pref[find(s)]; }
+};
+
+const int MAXN(21);
+trie A, B;
+char vis[MAXN * MAXN + 100][MAXN * MAXN + 100];
+int N, M;
+
+bool dfs(int a, int b) {
+  if (A.is_end(a) and B.is_end(b)) return true;
+
+  if (vis[a][b]) return false;
+
+  vis[a][b] = true;
+
+  bool ans = false;
+
+  if (A.next(a, '0') and B.next(b, '0'))
+    ans |= dfs(A.next(a, '0'), B.next(b, '0'));
+
+  if (A.next(a, '1') and B.next(b, '1'))
+    ans |= dfs(A.next(a, '1'), B.next(b, '1'));
+
+  if (A.is_end(a)) {
+    if (B.next(b, '1') and A.next(0, '1'))
+      ans |= dfs(A.next(0, '1'), B.next(b, '1'));
+
+    if (B.next(b, '0') and A.next(0, '0'))
+      ans |= dfs(A.next(0, '0'), B.next(b, '0'));
+  }
+
+  if (B.is_end(b)) {
+    if (A.next(a, '1') and B.next(0, '1'))
+      ans |= dfs(A.next(a, '1'), B.next(0, '1'));
+
+    if (A.next(a, '0') and B.next(0, '0'))
+      ans |= dfs(A.next(a, '0'), B.next(0, '0'));
+  }
+  return ans;
+}
+
+auto solve() {
+  A = trie(3, '0'), B = trie(4, '0');
+  memset(vis, 0, sizeof vis);
+
+  for (int i = 0; i < N; i++) {
+    string s;
+    cin >> s;
+    A.insert(s);
+  }
+
+  for (int i = 0; i < M; i++) {
+    string s;
+    cin >> s;
+    B.insert(s);
+  }
+
+  bool ans = false;
+  if (A.next(0, '0') and B.next(0, '0'))
+    ans |= dfs(A.next(0, '0'), B.next(0, '0'));
+
+  if (A.next(0, '1') and B.next(0, '1'))
+    ans |= dfs(A.next(0, '1'), B.next(0, '1'));
+
+  cout << "NS"[ans] << endl;
+}
+
+int32_t main(void) {
+#ifndef LOCAL
+  fastio;
+#endif
+
+  // cin >> t;
+
+  while (cin >> N >> M) {
+    solve();
+  }
+}
+
+// AC, strings, trie