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Submission #897228

# Submission time Handle Problem Language Result Execution time Memory
897228 2024-01-02T18:39:49 Z Kodik Mecho (IOI09_mecho) C++17
100 / 100
 533 ms 7628 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long  ll;
typedef long double ld;
typedef short int shit;

#define ff first
#define ss second


const int MAX_N = 800;
vector<string> field(MAX_N);
int n, s;
bool valid_sq(int x, int y) {
	return x >= 0 && x < n && y >= 0 && y < n &&
	       (field[x][y] == 'G' || field[x][y] == 'M');
}

bool mecho_reached(int mecho_dis, int bees_dis) {
	return mecho_dis / s < bees_dis;
}

int main(){
    ios_base::sync_with_stdio(false), cin.tie(NULL);
	// freopen("atlarge.in", "r", stdin);
	// freopen("atlarge.out", "w", stdout);
    cin >> n >> s;
	for (int i = 0; i < n; i++) { cin >> field[i]; }

	vector<pair<int, int>> hives;
	int mechox, mechoy, home_x, home_y;
	// find x and y coordinates for for Mecho, the bees and the cave
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (field[i][j] == 'M') {
				mechox = i;
				mechoy = j;
			} else if (field[i][j] == 'H') {
				hives.push_back({i, j});
			} else if (field[i][j] == 'D') {
				home_x = i;
				home_y = j;
			}
		}
	}

	int dx[] = {-1, 0, 1, 0};
	int dy[] = {0, -1, 0, 1};
    int l = 0;
	int r = n * n;
	while (l <= r) {
		vector<vector<bool>> bees_visited(n, vector<bool>(n));
		vector<vector<bool>> mecho_visited(n, vector<bool>(n));
		vector<vector<int>> bees_time(n, vector<int>(n));
		vector<vector<int>> mecho_time(n, vector<int>(n));
		queue<pair<int, int>> q;

		int eating_time = (l + r) / 2;

		// move bees
		for (auto i : hives) {
			q.push({i.first, i.second});
			bees_visited[i.first][i.second] = true;
		}

		while (!q.empty()) {
			int x = q.front().first, y = q.front().second;
			q.pop();
			for (int i = 0; i < 4; i++) {
				int nx = x + dx[i], ny = y + dy[i];
				if (valid_sq(nx, ny) && !bees_visited[nx][ny]) {
					bees_time[nx][ny] = bees_time[x][y] + 1;
					q.push({nx, ny});
					bees_visited[nx][ny] = true;
				}
			}
		}

		// move Mecho
		q.push({mechox, mechoy});
		mecho_visited[mechox][mechoy] = true;
		if (bees_time[mechox][mechoy] <= eating_time) { q.pop(); }

		while (!q.empty()) {
			int x = q.front().first, y = q.front().second;
			q.pop();
			for (int i = 0; i < 4; i++) {
				int nx = x + dx[i], ny = y + dy[i];
				/*
				 * check if mecho reaces node[x][y] before the bees
				 * divide the time mecho takes to reach a node by s, since
				 * mecho walks s steps at a time.
				 * substract the eating time from the time taken for the
				 * bees to reach the node, because that time was used by
				 * mecho for eating
				 */
				if (valid_sq(nx, ny) && !mecho_visited[nx][ny] &&
				    mecho_reached(mecho_time[x][y] + 1,
				                  bees_time[nx][ny] - eating_time)) {
					mecho_visited[nx][ny] = true;
					q.push({nx, ny});
					mecho_time[nx][ny] = mecho_time[x][y] + 1;
				}
			}
		}

		// check if mecho reached a node surrounding his cave before the bees
		bool reached = false;
		for (int i = 0; i < 4; i++) {
			int nx = home_x + dx[i], ny = home_y + dy[i];
			if (valid_sq(nx, ny) &&
			    mecho_reached(mecho_time[nx][ny],
			                  bees_time[nx][ny] - eating_time) &&
			    mecho_visited[nx][ny]) {
				reached = true;
			}
		}
		if (reached) {
			l = eating_time + 1;
		} else {
			r = eating_time - 1;
		}
	}

	cout << l - 1 << '\n';
    return 0; 
}

Compilation message

mecho.cpp: In function 'int main()':
mecho.cpp:82:23: warning: 'mechox' may be used uninitialized in this function [-Wmaybe-uninitialized]
   82 |   mecho_visited[mechox][mechoy] = true;
      |                       ^
mecho.cpp:111:29: warning: 'home_y' may be used uninitialized in this function [-Wmaybe-uninitialized]
  111 |    int nx = home_x + dx[i], ny = home_y + dy[i];
      |                             ^~
mecho.cpp:111:8: warning: 'home_x' may be used uninitialized in this function [-Wmaybe-uninitialized]
  111 |    int nx = home_x + dx[i], ny = home_y + dy[i];
      |        ^~

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 476 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 415 ms 7188 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 484 KB Output is correct
12 Correct 1 ms 348 KB Output is correct
13 Correct 1 ms 344 KB Output is correct
14 Correct 2 ms 348 KB Output is correct
15 Correct 1 ms 348 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 1 ms 344 KB Output is correct
18 Correct 1 ms 348 KB Output is correct
19 Correct 1 ms 348 KB Output is correct
20 Correct 1 ms 348 KB Output is correct
21 Correct 1 ms 600 KB Output is correct
22 Correct 1 ms 600 KB Output is correct
23 Correct 1 ms 480 KB Output is correct
24 Correct 1 ms 348 KB Output is correct
25 Correct 1 ms 348 KB Output is correct
26 Correct 1 ms 348 KB Output is correct
27 Correct 1 ms 348 KB Output is correct
28 Correct 2 ms 544 KB Output is correct
29 Correct 1 ms 348 KB Output is correct
30 Correct 1 ms 348 KB Output is correct
31 Correct 1 ms 348 KB Output is correct
32 Correct 1 ms 348 KB Output is correct
33 Correct 31 ms 1724 KB Output is correct
34 Correct 28 ms 1820 KB Output is correct
35 Correct 58 ms 1764 KB Output is correct
36 Correct 39 ms 2140 KB Output is correct
37 Correct 39 ms 2140 KB Output is correct
38 Correct 75 ms 2136 KB Output is correct
39 Correct 58 ms 2756 KB Output is correct
40 Correct 49 ms 2624 KB Output is correct
41 Correct 103 ms 2396 KB Output is correct
42 Correct 71 ms 3088 KB Output is correct
43 Correct 61 ms 3092 KB Output is correct
44 Correct 127 ms 3092 KB Output is correct
45 Correct 105 ms 3604 KB Output is correct
46 Correct 76 ms 3596 KB Output is correct
47 Correct 152 ms 3420 KB Output is correct
48 Correct 93 ms 4280 KB Output is correct
49 Correct 90 ms 4240 KB Output is correct
50 Correct 178 ms 4228 KB Output is correct
51 Correct 114 ms 4868 KB Output is correct
52 Correct 109 ms 4848 KB Output is correct
53 Correct 233 ms 4696 KB Output is correct
54 Correct 138 ms 5596 KB Output is correct
55 Correct 135 ms 5820 KB Output is correct
56 Correct 268 ms 5544 KB Output is correct
57 Correct 151 ms 6308 KB Output is correct
58 Correct 147 ms 6888 KB Output is correct
59 Correct 305 ms 6172 KB Output is correct
60 Correct 180 ms 7072 KB Output is correct
61 Correct 165 ms 7488 KB Output is correct
62 Correct 340 ms 7004 KB Output is correct
63 Correct 423 ms 7080 KB Output is correct
64 Correct 533 ms 7080 KB Output is correct
65 Correct 483 ms 7116 KB Output is correct
66 Correct 459 ms 7628 KB Output is correct
67 Correct 417 ms 7080 KB Output is correct
68 Correct 428 ms 7100 KB Output is correct
69 Correct 412 ms 7000 KB Output is correct
70 Correct 395 ms 7160 KB Output is correct
71 Correct 403 ms 7000 KB Output is correct
72 Correct 368 ms 7104 KB Output is correct
73 Correct 367 ms 7376 KB Output is correct
74 Correct 382 ms 7372 KB Output is correct
75 Correct 437 ms 7608 KB Output is correct
76 Correct 394 ms 7260 KB Output is correct
77 Correct 402 ms 7388 KB Output is correct
78 Correct 387 ms 7260 KB Output is correct
79 Correct 359 ms 7260 KB Output is correct
80 Correct 375 ms 7284 KB Output is correct
81 Correct 383 ms 7256 KB Output is correct
82 Correct 393 ms 7468 KB Output is correct
83 Correct 395 ms 7512 KB Output is correct
84 Correct 394 ms 7316 KB Output is correct
85 Correct 416 ms 7256 KB Output is correct
86 Correct 396 ms 7508 KB Output is correct
87 Correct 405 ms 7300 KB Output is correct
88 Correct 414 ms 7256 KB Output is correct
89 Correct 398 ms 7260 KB Output is correct
90 Correct 414 ms 7496 KB Output is correct
91 Correct 426 ms 7256 KB Output is correct
92 Correct 425 ms 7260 KB Output is correct