Submission #771014

#	Time	Username	Problem	Language	Result	Execution time	Memory
771014		ind1v	Mecho (IOI09_mecho)	C++11	100 / 100	157 ms	9484 KiB

mecho

#include <bits/stdc++.h>
 
using namespace std;
 
const int N = 805;
const int dI[4] = {-1, 0, +1, 0};
const int dJ[4] = {0, +1, 0, -1};
 
int n, s;
char a[N][N];
long long d[N][N];
int f[N][N];
bool can[N][N];
int mx, my, dx, dy;
 
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> s;
  memset(d, 0x3f, sizeof(d));
  memset(f, 0x3f, sizeof(f));
  queue<pair<int, int>> q;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      cin >> a[i][j];
      if (a[i][j] == 'H') {
        d[i][j] = 0;
        q.push({i, j});
      } else if (a[i][j] == 'M') {
        mx = i;
        my = j;
      } else if (a[i][j] == 'D') {
        dx = i;
        dy = j;
      }
    }
  }
  while (!q.empty()) {
    int x, y;
    tie(x, y) = q.front();
    q.pop();
    for (int dir = 0; dir < 4; dir++) {
      int nx = x + dI[dir];
      int ny = y + dJ[dir];
      if (1 <= nx && nx <= n && 1 <= ny && ny <= n && a[nx][ny] != 'D' && a[nx][ny] != 'T' && d[nx][ny] > d[x][y] + 1) {
        d[nx][ny] = d[x][y] + 1;
        q.push({nx, ny});
      }
    }
  }
  int l = 0, r = n * n, ans = -1;
  while (l <= r) {
    int m = (l + r) >> 1;
    memset(f, 0x3f, sizeof(f));
    memset(can, false, sizeof(can));
    queue<pair<int, int>> q;
    if (m < d[mx][my]) {
      f[mx][my] = 0;
      can[mx][my] = true;
      q.push({mx, my});
    }
    while (!q.empty()) {
      int x, y;
      tie(x, y) = q.front();
      q.pop();
      for (int dir = 0; dir < 4; dir++) {
        int nx = x + dI[dir];
        int ny = y + dJ[dir];
        if (1 <= nx && nx <= n && 1 <= ny && ny <= n && a[nx][ny] != 'T' && f[nx][ny] > f[x][y] + 1 && (f[x][y] + 1) / s + m < d[nx][ny] && !can[nx][ny]) {
          f[nx][ny] = f[x][y] + 1;
          can[nx][ny] = true;
          q.push({nx, ny});
        }
      }
    }
    if (can[dx][dy]) {
      ans = m;
      l = m + 1;
    } else {
      r = m - 1;
    }
  }
  cout << ans;
  return 0;
}

• Subtask 1: 100 / 100