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Submission #843989

# Submission time Handle Problem Language Result Execution time Memory
843989 2023-09-04T19:43:00 Z cryan Mecho (IOI09_mecho) C++17
91 / 100
 1000 ms 9040 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;
};
const vector<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 1 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 344 KB Output is correct
4 Correct 0 ms 344 KB Output is correct
5 Correct 0 ms 344 KB Output is correct
6 Correct 0 ms 344 KB Output is correct
7 Correct 39 ms 8120 KB Output is correct
8 Correct 0 ms 344 KB Output is correct
9 Correct 0 ms 344 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 344 KB Output is correct
12 Correct 0 ms 344 KB Output is correct
13 Correct 0 ms 344 KB Output is correct
14 Correct 1 ms 344 KB Output is correct
15 Correct 0 ms 344 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 0 ms 600 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 344 KB Output is correct
21 Correct 0 ms 344 KB Output is correct
22 Correct 0 ms 344 KB Output is correct
23 Correct 0 ms 344 KB Output is correct
24 Correct 0 ms 344 KB Output is correct
25 Correct 0 ms 344 KB Output is correct
26 Correct 0 ms 344 KB Output is correct
27 Correct 0 ms 344 KB Output is correct
28 Correct 0 ms 344 KB Output is correct
29 Correct 1 ms 544 KB Output is correct
30 Correct 0 ms 344 KB Output is correct
31 Correct 0 ms 344 KB Output is correct
32 Correct 1 ms 344 KB Output is correct
33 Correct 3 ms 1880 KB Output is correct
34 Correct 4 ms 1880 KB Output is correct
35 Correct 136 ms 2040 KB Output is correct
36 Correct 4 ms 2136 KB Output is correct
37 Correct 5 ms 2140 KB Output is correct
38 Correct 208 ms 2540 KB Output is correct
39 Correct 5 ms 2648 KB Output is correct
40 Correct 6 ms 2652 KB Output is correct
41 Correct 294 ms 3212 KB Output is correct
42 Correct 7 ms 3576 KB Output is correct
43 Correct 8 ms 3416 KB Output is correct
44 Correct 435 ms 3684 KB Output is correct
45 Correct 8 ms 3928 KB Output is correct
46 Correct 9 ms 3928 KB Output is correct
47 Correct 538 ms 4176 KB Output is correct
48 Correct 10 ms 4696 KB Output is correct
49 Correct 10 ms 4696 KB Output is correct
50 Correct 721 ms 5200 KB Output is correct
51 Correct 11 ms 5464 KB Output is correct
52 Correct 12 ms 5464 KB Output is correct
53 Correct 916 ms 6024 KB Output is correct
54 Correct 12 ms 6232 KB Output is correct
55 Correct 15 ms 6232 KB Output is correct
56 Execution timed out 1034 ms 6736 KB Time limit exceeded
57 Correct 14 ms 7000 KB Output is correct
58 Correct 17 ms 7000 KB Output is correct
59 Execution timed out 1053 ms 7872 KB Time limit exceeded
60 Correct 16 ms 8024 KB Output is correct
61 Correct 20 ms 8024 KB Output is correct
62 Execution timed out 1043 ms 9040 KB Time limit exceeded
63 Correct 37 ms 8020 KB Output is correct
64 Correct 40 ms 8016 KB Output is correct
65 Correct 39 ms 8024 KB Output is correct
66 Correct 36 ms 8024 KB Output is correct
67 Correct 38 ms 8024 KB Output is correct
68 Correct 29 ms 8016 KB Output is correct
69 Correct 33 ms 8016 KB Output is correct
70 Correct 28 ms 7884 KB Output is correct
71 Correct 28 ms 8024 KB Output is correct
72 Correct 31 ms 8016 KB Output is correct
73 Correct 25 ms 8024 KB Output is correct
74 Correct 58 ms 8040 KB Output is correct
75 Correct 25 ms 8016 KB Output is correct
76 Correct 27 ms 8024 KB Output is correct
77 Correct 27 ms 8024 KB Output is correct
78 Correct 27 ms 7968 KB Output is correct
79 Correct 302 ms 8180 KB Output is correct
80 Correct 46 ms 8144 KB Output is correct
81 Correct 28 ms 8024 KB Output is correct
82 Correct 89 ms 8028 KB Output is correct
83 Correct 30 ms 8028 KB Output is correct
84 Correct 80 ms 8024 KB Output is correct
85 Correct 146 ms 8180 KB Output is correct
86 Correct 189 ms 8272 KB Output is correct
87 Correct 46 ms 8024 KB Output is correct
88 Correct 104 ms 8024 KB Output is correct
89 Correct 346 ms 8272 KB Output is correct
90 Correct 35 ms 8024 KB Output is correct
91 Correct 56 ms 8028 KB Output is correct
92 Correct 36 ms 8024 KB Output is correct