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Submission #498316

# Submission time Handle Problem Language Result Execution time Memory
498316 2021-12-25T03:52:57 Z chenwz Mecho (IOI09_mecho) C++11
100 / 100
 179 ms 21572 KB 
// IOI2009 - Mecho
#include <bits/stdc++.h>
using namespace std;
const int NN = 2000 + 4, DX[4] = {1, -1, 0, 0}, DY[4] = {0, 0, 1, -1};
#define _for(i, a, b) for (int i = (a); i < (int)(b); ++i)
string G[NN];
int N, S, D[NN][NN];
bool Vis[NN][NN];
struct Point {
  int x, y;
};
bool valid(int x, int y) {
  return 0 <= x && x < N && 0 <= y && y < N;
  // nx < 0 || nx >= N || ny < 0 || ny >= N
}
bool check(const Point& st, const Point& ed,
           int delay) {  // 小熊delay再出发够不?
  if (delay * S >= D[st.x][st.y]) return false;
  queue<pair<int, Point> > Q;  // {当前时间，当前位置}
  memset(Vis, 0, sizeof(Vis)), Q.push({delay * S, st}), Vis[st.x][st.y] = true;
  while (!Q.empty()) {
    auto p = Q.front();
    Q.pop();
    int d = p.first, x = p.second.x, y = p.second.y;
    // if (G[x][y] == 'D')
    if (x == ed.x && y == ed.y) return true;  // 到家
    _for(i, 0, 4) {
      int nx = x + DX[i], ny = y + DY[i];
      if (valid(nx, ny) && G[nx][ny] != 'T' && d + 1 < D[nx][ny] &&
          !Vis[nx][ny])
        // if (nx < 0 || nx >= N || ny < 0 || ny >= N || G[nx][ny] == 'T' ||
        //     (d + 1) >= D[nx][ny] || Vis[nx][ny])
        //   continue;
        Q.push({d + 1, {nx, ny}}), Vis[nx][ny] = true;
    }
  }
  return false;
}
int main() {
  ios::sync_with_stdio(false), cin.tie(0);
  cin >> N >> S;
  queue<Point> Q;
  Point st, ed;
  memset(D, -1, sizeof(D));
  _for(i, 0, N) {
    cin >> G[i];
    _for(j, 0, N) {
      char& c = G[i][j];
      if (c == 'H') Q.push({i, j}), D[i][j] = 0;
      if (c == 'M') st = {i, j}, c = 'G';  // 初始小熊位置也改成草
      if (c == 'D') ed = {i, j};           // 家的位置
    }
  }
  while (!Q.empty()) {  // BFS计算每个点到最近的蜜蜂的距离
    Point p = Q.front();
    Q.pop();
    _for(i, 0, 4) {
      int nx = p.x + DX[i], ny = p.y + DY[i], &nd = D[nx][ny];
      if (valid(nx, ny) && G[nx][ny] == 'G' && nd == -1)
        // if (!valid(nx, ny) || G[nx][ny] != 'G' || D[nx][ny] != -1) continue;
        nd = D[p.x][p.y] + S, Q.push({nx, ny});
    }
  }
  D[ed.x][ed.y] = N * N * S;
  int L = -1, R = 2 * N * N;
  while (L + 1 < R) {
    int mid = (L + R) / 2;  // 推迟mid出发够不够
    (check(st, ed, mid) ? L : R) = mid;
  }
  cout << L << endl;
  return 0;
}
// 2021-12-20 Mecho (IOI09_mecho) C++11 100/100 180 ms 21600 KB

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 19952 KB Output is correct
2 Correct 10 ms 19892 KB Output is correct
3 Correct 10 ms 19960 KB Output is correct
4 Correct 11 ms 19916 KB Output is correct
5 Correct 8 ms 19916 KB Output is correct
6 Correct 9 ms 19968 KB Output is correct
7 Correct 81 ms 21416 KB Output is correct
8 Correct 9 ms 19972 KB Output is correct
9 Correct 10 ms 19916 KB Output is correct
10 Correct 9 ms 19916 KB Output is correct
11 Correct 8 ms 19916 KB Output is correct
12 Correct 9 ms 19916 KB Output is correct
13 Correct 8 ms 19916 KB Output is correct
14 Correct 9 ms 19940 KB Output is correct
15 Correct 9 ms 19916 KB Output is correct
16 Correct 9 ms 20012 KB Output is correct
17 Correct 8 ms 19916 KB Output is correct
18 Correct 9 ms 19908 KB Output is correct
19 Correct 10 ms 19948 KB Output is correct
20 Correct 8 ms 19916 KB Output is correct
21 Correct 10 ms 19916 KB Output is correct
22 Correct 9 ms 20028 KB Output is correct
23 Correct 9 ms 19916 KB Output is correct
24 Correct 12 ms 20028 KB Output is correct
25 Correct 9 ms 19916 KB Output is correct
26 Correct 10 ms 19916 KB Output is correct
27 Correct 11 ms 19916 KB Output is correct
28 Correct 9 ms 19964 KB Output is correct
29 Correct 11 ms 20044 KB Output is correct
30 Correct 12 ms 19972 KB Output is correct
31 Correct 9 ms 19916 KB Output is correct
32 Correct 9 ms 20044 KB Output is correct
33 Correct 15 ms 20236 KB Output is correct
34 Correct 11 ms 20228 KB Output is correct
35 Correct 26 ms 20216 KB Output is correct
36 Correct 11 ms 20264 KB Output is correct
37 Correct 11 ms 20256 KB Output is correct
38 Correct 41 ms 20332 KB Output is correct
39 Correct 13 ms 20360 KB Output is correct
40 Correct 13 ms 20364 KB Output is correct
41 Correct 41 ms 20364 KB Output is correct
42 Correct 13 ms 20488 KB Output is correct
43 Correct 15 ms 20520 KB Output is correct
44 Correct 49 ms 20468 KB Output is correct
45 Correct 18 ms 20608 KB Output is correct
46 Correct 16 ms 20620 KB Output is correct
47 Correct 50 ms 20556 KB Output is correct
48 Correct 15 ms 20740 KB Output is correct
49 Correct 13 ms 20740 KB Output is correct
50 Correct 60 ms 20736 KB Output is correct
51 Correct 16 ms 20804 KB Output is correct
52 Correct 14 ms 20872 KB Output is correct
53 Correct 92 ms 20812 KB Output is correct
54 Correct 17 ms 21016 KB Output is correct
55 Correct 15 ms 20940 KB Output is correct
56 Correct 84 ms 21060 KB Output is correct
57 Correct 17 ms 21056 KB Output is correct
58 Correct 16 ms 21128 KB Output is correct
59 Correct 95 ms 21052 KB Output is correct
60 Correct 19 ms 21256 KB Output is correct
61 Correct 16 ms 21192 KB Output is correct
62 Correct 119 ms 21208 KB Output is correct
63 Correct 106 ms 21236 KB Output is correct
64 Correct 179 ms 21308 KB Output is correct
65 Correct 139 ms 21188 KB Output is correct
66 Correct 112 ms 21224 KB Output is correct
67 Correct 106 ms 21228 KB Output is correct
68 Correct 52 ms 21332 KB Output is correct
69 Correct 52 ms 21328 KB Output is correct
70 Correct 37 ms 21248 KB Output is correct
71 Correct 40 ms 21248 KB Output is correct
72 Correct 30 ms 21264 KB Output is correct
73 Correct 30 ms 21504 KB Output is correct
74 Correct 54 ms 21560 KB Output is correct
75 Correct 70 ms 21496 KB Output is correct
76 Correct 62 ms 21560 KB Output is correct
77 Correct 58 ms 21488 KB Output is correct
78 Correct 71 ms 21468 KB Output is correct
79 Correct 48 ms 21548 KB Output is correct
80 Correct 70 ms 21556 KB Output is correct
81 Correct 67 ms 21564 KB Output is correct
82 Correct 56 ms 21552 KB Output is correct
83 Correct 78 ms 21512 KB Output is correct
84 Correct 65 ms 21572 KB Output is correct
85 Correct 72 ms 21504 KB Output is correct
86 Correct 71 ms 21512 KB Output is correct
87 Correct 71 ms 21452 KB Output is correct
88 Correct 90 ms 21388 KB Output is correct
89 Correct 74 ms 21376 KB Output is correct
90 Correct 86 ms 21464 KB Output is correct
91 Correct 78 ms 21460 KB Output is correct
92 Correct 81 ms 21444 KB Output is correct