답안 #897228

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
897228	2024-01-02T18:39:49 Z	Kodik	Mecho (IOI09_mecho)	C++17	100 / 100	533 ms	7628 KB

mecho

#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

#	결과	실행 시간	메모리	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