Submission #1256647

#	Time	Username	Problem	Language	Result	Execution time	Memory
1256647		aeg	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	620 ms	75536 KiB

tracks

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

int main() {
  cin.tie(0)->sync_with_stdio(0);
  int h, w;
  cin >> h >> w;
  vector<vector<int>> a(h, vector<int>(w));
  for (auto &x : a) {
    for (auto &y : x) {
      char c;
      cin >> c;
      if (c == '.')
        y = 0;
      else if (c == 'R')
        y = 1;
      else
        y = 2;
    }
  }

  int st = a[0][0];
  int ans = 0;
  queue<pair<int, int>> cur, oth;
  cur.push({0, 0});
  vector<vector<bool>> vis(h, vector<bool>(w, false));
  vis[0][0] = true;
  while (!cur.empty()) {
    ans++;

    while (!cur.empty()) {
      auto &[i, j] = cur.front();
      cur.pop();
      if (i != 0) {
        if (!vis[i - 1][j] && a[i - 1][j]) {
          vis[i - 1][j] = true;
          if (a[i - 1][j] == st)
            cur.push({i - 1, j});
          else
            oth.push({i - 1, j});
        }
      }
      if (i != h - 1) {
        if (!vis[i + 1][j] && a[i + 1][j]) {
          vis[i + 1][j] = true;
          if (a[i + 1][j] == st)
            cur.push({i + 1, j});
          else
            oth.push({i + 1, j});
        }
      }
      if (j != 0) {
        if (!vis[i][j - 1] && a[i][j - 1]) {
          vis[i][j - 1] = true;
          if (a[i][j - 1] == st)
            cur.push({i, j - 1});
          else
            oth.push({i, j - 1});
        }
      }
      if (j != w - 1) {
        if (!vis[i][j + 1] && a[i][j + 1]) {
          vis[i][j + 1] = true;
          if (a[i][j + 1] == st)
            cur.push({i, j + 1});
          else
            oth.push({i, j + 1});
        }
      }
    }

    st ^= 3;
    swap(cur, oth);
  }

  cout << ans << '\n';
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70