Submission #800634

#	Time	Username	Problem	Language	Result	Execution time	Memory
800634		tch1cherin	Portals (BOI14_portals)	C++17	100 / 100	289 ms	27696 KiB

portals

#include <bits/stdc++.h>
using namespace std;

template <typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int N, M;
  cin >> N >> M;
  vector<string> S(N + 2, string(M + 2, '#'));
  for (int i = 1; i <= N; i++) {
    string v;
    cin >> v;
    for (int j = 1; j <= M; j++) {
      S[i][j] = v[j - 1];
    }
  }
  N += 2, M += 2;
  vector<vector<int>> up(N, vector<int>(M, -1)), down(N, vector<int>(M, -1));
  vector<vector<int>> left(N, vector<int>(M, -1)), right(N, vector<int>(M, -1));
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      if (S[i][j] != '#') {
        up[i][j] = up[i - 1][j] + 1;
        left[i][j] = left[i][j - 1] + 1;
      }
    }
  }
  for (int i = N - 1; i >= 0; i--) {
    for (int j = M - 1; j >= 0; j--) {
      if (S[i][j] != '#') {
        down[i][j] = down[i + 1][j] + 1;
        right[i][j] = right[i][j + 1] + 1;
      }
    }
  }
  queue<pair<int, int>> q;
  vector<vector<int>> nearest_wall(N, vector<int>(M, INT_MAX));
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      if (S[i][j] == '#') {
        q.push({i, j});
        nearest_wall[i][j] = 0;
      }
    }
  }
  while (!q.empty()) {
    auto [x, y] = q.front();
    q.pop();
    for (auto [dx, dy] : vector<pair<int, int>> {{-1, 0}, {1, 0}, {0, -1}, {0, 1}}) {
      int i = x + dx, j = y + dy;
      if (i >= 0 && j >= 0 && i < N && j < M && nearest_wall[i][j] == INT_MAX) {
        nearest_wall[i][j] = nearest_wall[x][y] + 1;
        q.push({i, j});
      }
    }
  }
  min_heap<tuple<int, int, int>> pq;
  vector<vector<int>> dist(N, vector<int>(M, INT_MAX));
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      if (S[i][j] == 'S') {
        pq.push({dist[i][j] = 0, i, j});
      }
    }
  }
  while (!pq.empty()) {
    auto [d, x, y] = pq.top();
    pq.pop();
    if (d == dist[x][y]) {
      for (auto [dx, dy] : vector<pair<int, int>> {{-1, 0}, {1, 0}, {0, -1}, {0, 1}, 
                          {-up[x][y], 0}, {down[x][y], 0}, {0, -left[x][y]}, {0, right[x][y]}}) {
        int w = max(abs(dx), abs(dy)) == 1 ? 1 : nearest_wall[x][y];
        int i = x + dx, j = y + dy;
        if (i >= 0 && i < N && j >= 0 && j < M && S[i][j] != '#' && dist[i][j] > dist[x][y] + w) {
          pq.push({dist[i][j] = dist[x][y] + w, i, j});
        }
      }
    }
  }
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      if (S[i][j] == 'C') {
        cout << dist[i][j] << "\n";
      }
    }
  }
}

• Subtask 1: 11 / 11
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 19 / 19
• Subtask 5: 30 / 30