Submission #494345

#	Time	Username	Problem	Language	Result	Execution time	Memory
494345		MilosMilutinovic	Portals (BOI14_portals)	C++14	20 / 100	11 ms	4812 KiB

portals

#include <bits/stdc++.h>

using namespace std;

const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, 1, -1};

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<string> s(n);
  for (int i = 0; i < n; i++) {
    cin >> s[i];
  }
  int sx, sy, cx, cy;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] == 'S') {
        sx = i;
        sy = j;
      }
      if (s[i][j] == 'C') {
        cx = i;
        cy = j;
      }
    }
  }
  vector<vector<pair<int, int>>> up(n, vector<pair<int, int>>(m));
  vector<vector<pair<int, int>>> down(n, vector<pair<int, int>>(m));
  vector<vector<pair<int, int>>> left(n, vector<pair<int, int>>(m));
  vector<vector<pair<int, int>>> right(n, vector<pair<int, int>>(m));
  //up
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] != '#') {
        if (i == 0 || up[i - 1][j] == make_pair(-1, -1)) {
          up[i][j] = make_pair(i, j);
        } else {
          up[i][j] = up[i - 1][j];
        }
      } else {
        up[i][j] = make_pair(-1, -1);
      }
    }
  }
  //down
  for (int i = n - 1; i >= 0; i--) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] != '#') {
        if (i == n - 1 || down[i + 1][j] == make_pair(-1, -1)) {
          down[i][j] = make_pair(i, j);
        } else {
          down[i][j] = down[i + 1][j];
        }
      } else {
        down[i][j] = make_pair(-1, -1);
      }
    }
  }
  //left
  for (int j = 0; j < m; j++) {
    for (int i = 0; i < n; i++) {
      if (s[i][j] != '#') {
        if (j == 0 || left[i][j - 1] == make_pair(-1, -1)) {
          left[i][j] = make_pair(i, j);
        } else {
          left[i][j] = left[i][j - 1];
        }
      } else {
        left[i][j] = make_pair(-1, -1);
      }
    }
  }
  //right
  for (int j = m - 1; j >= 0; j--) {
    for (int i = 0; i < n; i++) {
      if (s[i][j] != '#') {
        if (j == m - 1 || right[i][j + 1] == make_pair(-1, -1)) {
          right[i][j] = make_pair(i, j);
        } else {
          right[i][j] = right[i][j + 1];
        }
      } else {
        right[i][j] = make_pair(-1, -1);
      }
    }
  }
  /*for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cout << "{" << up[i][j].first << ", " << up[i][j].second << "}" << " ";
    }
    cout << "\n";
  }*/
  vector<vector<vector<pair<int, int>>>> g(n, vector<vector<pair<int, int>>>(m));
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '#') continue;
      bool ok = false;
      if (up[i][j] == make_pair(i, j)) {
        ok = true;
      }
      if (down[i][j] == make_pair(i, j)) {
        ok = true;
      }
      if (left[i][j] == make_pair(i, j)) {
        ok = true;
      }
      if (right[i][j] == make_pair(i, j)) {
        ok = true;
      }
      if (ok) {
        if (up[i][j] != make_pair(-1, -1)) {
          g[i][j].push_back(up[i][j]);
        }
        if (down[i][j] != make_pair(-1, -1)) {
          g[i][j].push_back(down[i][j]);
        }
        if (left[i][j] != make_pair(-1, -1)) {
          g[i][j].push_back(left[i][j]);
        }
        if (right[i][j] != make_pair(-1, -1)) {
          g[i][j].push_back(right[i][j]);
        }
      }
      for (int foo = 0; foo < 4; foo++) {
        int ni = i + dx[foo], nj = j + dy[foo];
        if (ni >= 0 && ni < n && nj >= 0 && nj < m && s[ni][nj] != '#') {
          g[i][j].push_back(make_pair(ni, nj));
        }
      }
    }
  }
  deque<pair<int, int>> q;
  q.emplace_back(sx, sy);
  vector<vector<int>> dist(n, vector<int>(m, -1));
  dist[sx][sy] = 0;
  while (!q.empty()) {
    int x = q[0].first;
    int y = q[0].second;
    q.pop_front();
    for (auto c : g[x][y]) {
      if (dist[c.first][c.second] == -1) {
        dist[c.first][c.second] = dist[x][y] + 1;
        q.emplace_back(c.first, c.second);
      }
    }
  }
  cout << dist[cx][cy];
  return 0;
}

Compilation message (stderr)

portals.cpp: In function 'int main()':
portals.cpp:150:22: warning: 'cy' may be used uninitialized in this function [-Wmaybe-uninitialized]
  150 |   cout << dist[cx][cy];
      |                      ^
portals.cpp:150:18: warning: 'cx' may be used uninitialized in this function [-Wmaybe-uninitialized]
  150 |   cout << dist[cx][cy];
      |                  ^

• Subtask 1: 0 / 11
• Subtask 2: 0 / 20
• Subtask 3: 20 / 20
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30