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Submission #843991

# Submission time Handle Problem Language Result Execution time Memory
843991 2023-09-04T19:46:18 Z cryan Mecho (IOI09_mecho) C++17
91 / 100
 1000 ms 9224 KB 
// oh, these hills, they burn so bright / oh, these hills, they bring me life
#include "bits/stdc++.h"
using namespace std;

using ll = long long;
#define all(x) begin(x), end(x)
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)(x.size())
#define inf 1000000010
#define linf 0x3f3f3f3f3f3f3f3f
#define mp make_pair
#define f first
#define s second
#define pi pair<int, int>
#ifdef LOCAL
#include "/mnt/c/yukon/pp.hpp"
#else
#define endl '\n'
#endif

struct Event {
	pi loc;
	int dist;
};
int grid[801][801];
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
int main() {
	cin.tie(0)->sync_with_stdio(0);

	int n;
	cin >> n;

	int S;
	cin >> S;

	vector<vector<int>> grid(n, vector<int>(n));
	vector<pi> hives;
	pi start, end;

	for (int i = 0; i < n; i++) {
		string st;
		cin >> st;

		for (int j = 0; j < n; j++) {
			if (st[j] == 'T')
				grid[i][j] = -1;
			else if (st[j] != 'D')
				grid[i][j] = 0;
			else
				grid[i][j] = 1, end = {i, j};

			if (st[j] == 'H') {
				hives.emplace_back(i, j);
			} else if (st[j] == 'M')
				start = {i, j};
		}
	}

	// let's get distance from bees first
	queue<Event> bfs;

	vector<vector<int>> dist_bees(n, vector<int>(n, inf));
	for (auto &[i, j] : hives) {
		bfs.push({{i, j}, 0});
		dist_bees[i][j] = 0;
	}
	while (!bfs.empty()) {
		auto [i, j] = bfs.front().loc;
		int dist = bfs.front().dist;
		bfs.pop();

		if (dist_bees[i][j] < dist)
			continue;

		for (int d = 0; d < 4; d++) {
			int new_i = i + dx[d], new_j = j + dy[d];

			if (new_i >= 0 && new_i < n && new_j >= 0 && new_j < n) {
				if (grid[new_i][new_j] != -1 && dist_bees[new_i][new_j] > dist + 1 && pi{new_i, new_j} != end) {
					dist_bees[new_i][new_j] = dist + 1;
					bfs.push({{new_i, new_j}, dist + 1});
				}
			}
		}
	}
	// for (int i = 0; i < n; i++) {
	// 	cout << dist_bees[i] << endl;
	// }

	// now mecho's turn
	bfs.push({{start.f, start.s}, 0});
	// just store distance w/o S factor
	vector<vector<int>> mecho_dist(n, vector<int>(n, -inf));
	mecho_dist[start.f][start.s] = dist_bees[start.f][start.s];

	while (sz(bfs)) {
		auto [i, j] = bfs.front().loc;
		int dist = bfs.front().dist;
		bfs.pop();
		if (mecho_dist[i][j] > dist_bees[i][j] - (dist) / S)
			continue;
		for (int d = 0; d < 4; d++) {
			int ni = i + dx[d], nj = j + dy[d];

			if (ni < 0 || ni >= n || nj < 0 || nj >= n)
				continue;

			int elapsed = (dist + 1) / S;
			// if (ni == 3 && nj == 3) {
			// 	cout << dist + 1 << ' ' << elapsed << ' ' << dist_bees[ni][nj] << endl;
			// }
			int lead = min(mecho_dist[i][j], dist_bees[ni][nj] - elapsed);
			if (grid[ni][nj] != -1 && mecho_dist[ni][nj] < lead && elapsed < dist_bees[ni][nj]) {
				mecho_dist[ni][nj] = lead;
				bfs.push({{ni, nj}, dist + 1});
			}
		}
	}
	// cout << "________" << endl;
	// for (int i = 0; i < n; i++) {
	// 	cout << mecho_dist[i] << endl;
	// }
	// cout << "________" << endl;
	// for (int i = 0; i < n; i++) {
	// 	cout << mecho_lead[i] << endl;
	// }

	int ans = -inf;
	for (int d = 0; d < 4; d++) {
		int ni = end.f + dx[d], nj = end.s + dy[d];

		if (ni < 0 || ni >= n || nj < 0 || nj >= n)
			continue;
		if (grid[ni][nj] == -1 || mecho_dist[ni][nj] == inf)
			continue;

		ans = max(ans, mecho_dist[ni][nj] - 1);
		// int elapsed = (mecho_dist[ni][nj] + S) / S;
		// ans = max(ans, dist_bees[ni][nj] - elapsed);
	}
	if (ans < 0) {
		cout << -1 << endl;
	} else {
		cout << ans << endl;
	}
}

// don't get stuck on one approach
// question bounds
// flesh out your approach before implementing o.o
// math it out
// ok well X is always possible, how about X + 1 (etc.)

Subtask #1
91.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 1 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 42 ms 8020 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 348 KB Output is correct
12 Correct 0 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 0 ms 348 KB Output is correct
16 Correct 0 ms 348 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 0 ms 344 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 0 ms 348 KB Output is correct
21 Correct 1 ms 344 KB Output is correct
22 Correct 0 ms 344 KB Output is correct
23 Correct 0 ms 348 KB Output is correct
24 Correct 0 ms 348 KB Output is correct
25 Correct 0 ms 348 KB Output is correct
26 Correct 0 ms 348 KB Output is correct
27 Correct 0 ms 348 KB Output is correct
28 Correct 0 ms 348 KB Output is correct
29 Correct 0 ms 348 KB Output is correct
30 Correct 0 ms 348 KB Output is correct
31 Correct 0 ms 348 KB Output is correct
32 Correct 0 ms 348 KB Output is correct
33 Correct 3 ms 1884 KB Output is correct
34 Correct 4 ms 1884 KB Output is correct
35 Correct 145 ms 1976 KB Output is correct
36 Correct 4 ms 2392 KB Output is correct
37 Correct 5 ms 2392 KB Output is correct
38 Correct 222 ms 2536 KB Output is correct
39 Correct 5 ms 2652 KB Output is correct
40 Correct 7 ms 2908 KB Output is correct
41 Correct 293 ms 3096 KB Output is correct
42 Correct 7 ms 3420 KB Output is correct
43 Correct 9 ms 3484 KB Output is correct
44 Correct 414 ms 3548 KB Output is correct
45 Correct 8 ms 3932 KB Output is correct
46 Correct 9 ms 3932 KB Output is correct
47 Correct 542 ms 4488 KB Output is correct
48 Correct 9 ms 4700 KB Output is correct
49 Correct 11 ms 4792 KB Output is correct
50 Correct 715 ms 5148 KB Output is correct
51 Correct 11 ms 5464 KB Output is correct
52 Correct 13 ms 5468 KB Output is correct
53 Correct 915 ms 5940 KB Output is correct
54 Correct 13 ms 6236 KB Output is correct
55 Correct 14 ms 6200 KB Output is correct
56 Execution timed out 1068 ms 6928 KB Time limit exceeded
57 Correct 14 ms 6992 KB Output is correct
58 Correct 17 ms 7004 KB Output is correct
59 Execution timed out 1067 ms 7624 KB Time limit exceeded
60 Correct 16 ms 8028 KB Output is correct
61 Correct 19 ms 8028 KB Output is correct
62 Execution timed out 1052 ms 9224 KB Time limit exceeded
63 Correct 35 ms 8024 KB Output is correct
64 Correct 39 ms 8016 KB Output is correct
65 Correct 38 ms 8024 KB Output is correct
66 Correct 36 ms 8024 KB Output is correct
67 Correct 31 ms 8024 KB Output is correct
68 Correct 29 ms 8016 KB Output is correct
69 Correct 33 ms 8028 KB Output is correct
70 Correct 28 ms 7908 KB Output is correct
71 Correct 27 ms 8224 KB Output is correct
72 Correct 30 ms 7916 KB Output is correct
73 Correct 26 ms 8028 KB Output is correct
74 Correct 57 ms 8016 KB Output is correct
75 Correct 25 ms 8028 KB Output is correct
76 Correct 26 ms 8028 KB Output is correct
77 Correct 28 ms 8028 KB Output is correct
78 Correct 28 ms 8008 KB Output is correct
79 Correct 295 ms 8156 KB Output is correct
80 Correct 44 ms 8028 KB Output is correct
81 Correct 29 ms 8028 KB Output is correct
82 Correct 84 ms 8148 KB Output is correct
83 Correct 31 ms 7944 KB Output is correct
84 Correct 77 ms 8148 KB Output is correct
85 Correct 142 ms 8200 KB Output is correct
86 Correct 190 ms 8276 KB Output is correct
87 Correct 56 ms 8024 KB Output is correct
88 Correct 104 ms 8228 KB Output is correct
89 Correct 354 ms 8532 KB Output is correct
90 Correct 37 ms 8024 KB Output is correct
91 Correct 54 ms 8148 KB Output is correct
92 Correct 36 ms 8024 KB Output is correct